Exhibit 8.1

Principal subsidiaries

The following is a list of Ternium’s subsidiaries at December 31, 2007.

Company	Country of Organization	Main activity
Hylsamex S.A. de C.V. (1)	Mexico	Holding company
Siderar S.A.I.C.	Argentina	Manufacturing of flat steel products
Sidor C.A. (2)	Venezuela	Manufacturing and selling of steel products
Ternium Internacional S.A. (formerly Techintrade Uruguay S.A.)	Uruguay	Holding company and marketing of steel products
I.I.I. Industrial Investments Inc., S.A. de C.V. (3)	Mexico	Holding company
Inversiones Siderúrgicas S.A.	Panama	Holding company
Ylopa—Servicios de Consultadoria Lda. (4)	Madeira - Free zone	Participation in the debt restructuring process of Amazonia and Sidor C.A.
Consorcio Siderurgia Amazonia Ltd.(5)	Cayman Islands	Holding of investments in Venezuelan steel companies
Fasnet International S.A.	Panama	Holding company
Alvory S.A.	Uruguay	Holding of investment in procurement services companies
Comesi San Luis S.A.I.C. (6)	Argentina	Production of cold or hot rolled prepainted, formed and skelped steel sheets
Inversiones Basilea S.A. (7)	Chile	Purchase and sale of real estate and other
Prosid Investments S.C.A.(7)	Uruguay	Holding company
Impeco S.A. (7)	Argentina	Manufacturing of pipe products
Socominter de Guatemala S.A. (8)	Guatemala	Marketing of steel products
Ternium Internacional España S.A. (formerly Socominter de España S.A.U.) (8)	Spain	Marketing of steel products
Ternium Internacional Ecuador S.A. (formerly Socotrading S.A.) (8)	Ecuador	Marketing of steel products
Ternium International USA Corporation (formerly Techintrade Corporation) (8)	USA	Marketing of steel products
Ternium Internationaal B.V. (formerly Techint Engineering Company B.V.)(8)	Netherlands	Marketing of steel products
Ternium Internacional Perú S.A.C. (formerly Techintrade del Perú S.A.C.) (8)	Peru	Marketing of steel products
Ternium International Inc.(8)	Panama	Marketing of steel products
Hylsa S.A. de C.V. (9)	Mexico	Manufacturing and selling of steel products
Ferropak Comercial S.A. de C.V. (9)	Mexico	Scrap company
Ferropak Servicios S.A. de C.V. (9)	Mexico	Services
Galvacer America Inc (9)	USA	Distributing company
Galvamet America Corp (9)	USA	Manufacturing and selling of insulates panel products
Transamerica E. & I. Trading Corp (9)	USA	Scrap company
Galvatubing Inc. (9)	USA	Manufacturing and selling of pipe products
Las Encinas S.A. de C.V. (9)	Mexico	Exploration, exploitation and pelletizing of iron ore
Técnica Industrial S.A. de C.V. (9)	Mexico	Services
Acerex S.A. de C.V.	Mexico	Tooling services

Company	Country of Organization	Main activity
Acerex Servicios S.A. de C.V.	Mexico	Services
Consorcio Minero Benito Juarez Peña Colorada S.A.de C.V. (10)	Mexico	Exploration, explotation and pelletizing of iron ore
Peña Colorada Servicios S.A. de C.V. (10)	Mexico	Services
Ternium Treasury Services S.A.	Uruguay	Financial Services
Ternium Treasury Services B.V	Holanda	Financial Services
Servicios Integrales Nova de Monterrey S.A. de C.V. (11)	Mexico	Medical and Social Services
Ternium Mexico S.A. de C.V. (formerly Grupo Imsa S.A.B. de C.V.)	Mexico	Holding company
Imsa Acero S.A. de C.V. (12)	Mexico	Holding company
Enermex S.A. de C.V. (12)	Mexico	Holding company
Sefimsa S.A. de C.V. (12)	Mexico	Financial Services
Ecore Holding S. de R.L. de C.V. (12)	Mexico	Holding company
Neotec L.L.C. (12)	USA	Holding company
Treasury Services L.L.C. (12)	USA	Financial Services
APM, S.A. de C.V.	Mexico	Manufacturing and selling of steel products
Acedor, S.A. de C.V.	Mexico	Holding company
Empresas Stabilit S.A. de C.V. (12)	Mexico	Holding company
Acerus S.A. de C.V. (12)	Mexico	Manufacturing and selling of steel products
Imsa Monclova S.A. de C.V. (12)	Mexico	Services
Imsamex Ecuador S.A. (12)	Ecuador	Marketing of steel products
Industrias Monterrey S.A. (12)	Guatemala	Manufacturing and selling of steel products
Imsaacero Ecuador Holding S.A. (12)	Ecuador	Holding company
Corporativo Grupo Imsa S.A. de C.V. (12)	Mexico	Services
Industrias Monterrey S.A. de C.V. (12)	Mexico	Manufacturing and selling of steel products
Ternium USA Inc. (formerly Imsa holding Inc.) (12)	USA	Holding company
Industria Galvanizadora S.A. (12)	Guatemala	Manufacturing and selling of steel products
Imsa Americas Inc. (12)	USA	Marketing of steel products

Company	Country of Organization	Main activity
Imsa Caribbean Inc. (12)	Puerto Rico	Manufacturing and selling of steel products
Imsa Colombia S.A. (12)	Colombia	Marketing of steel products
Imsa Andina S.A. (12)	Peru	Marketing of steel products
Multypanel de América S.A. (12)	Costa Rica	Manufacturing and selling of insulated panel products
Industria Galvanizadora S.A. (12)	Nicaragua	Manufacturing and selling of steel products
Industria Galvanizadora de Honduras S.A. de C.V. (12)	Honduras	Manufacturing and selling of steel products
Industria Galvanizadora S.A. de C.V. (12)	El Salvador	Manufacturing and selling of steel products
Industrias Monterrey S.A. (12)	Costa Rica	Manufacturing and selling of steel products

(1) Indirectly through the participation of Ternium Mexico S.A. de C.V. (70.00%) and Siderar S.A.I.C. (29.92%). Total voting rights held: 99.92%.

(2) Indirectly through the participation in Amazonia (59.73%). Total voting rights held: 59.73%. In April 2008, the Venezuelan government announced its intention to nationalize Sidor. For more information on the Sidor nationalization process, see Item 4. “Information on the Company—A. History and Development of the Company—Sidor Nationalization Process.”

(3) Formerly I.I.I.-Industrial Investment Inc. As of December 13, 2007 it was merged into Ternium México S.A. de C.V.

(4) Directly (88.89%), indirectly through Prosid Investments S.C.A. (11.11%). Total voting rights held: 100.00%.

(5) Directly (85.62%) and indirectly through the participation in Prosid Investments S.C.A. (14.38%). Total voting rights held: 100.00%.

(6) Indirectly through Siderar S.A.I.C. (99.00%) and Ternium Internacional Uruguay S.A. (1.00%). Total voting rights held: 100.00%.

(7) Indirectly through Siderar S.A.I.C. Total voting rights held 100.00%.

(8) Indirectly through Ternium Internacional S.A. of Uruguay.

(9) Indirectly through the participation in Hylsamex. Total voting rights held: 99.92%. See note 3(e) to the Company’s audited consolidated financial statements included in this annual report.

(10) Indirectly through the participation in Hylsamex. Total voting rights held: 50.00%.

(11) Incorporated during 2007.

(12) Subsidiary of Ternium Mexico S.A. de C.V. See note 3(a) to the Company’s audited consolidated financial statements included in this annual report.