Exhibit 8.1

Organizational Structure

At December 31, 2005, we had the following principal subsidiary undertakings:

		Group		Registered Office &
		Share		Country of Incorporation &
Company	Nature of Business	%		Operation
Athena Neurosciences, Inc.	Holding company		100	800 Gateway Blvd South San Francisco, CA, United States
Elan Capital Corporation, Ltd.	Financial services company		100	Clarendon House, 2 Church St Hamilton, Bermuda
Elan Drug Delivery, Inc.	R&D		100	3000 Horizon Drive King of Prussia, PA, United States
Elan Finance, plc	Financial services company		100	Treasury Building, Lower Grand Canal Street, Dublin 2, Ireland
Elan Holdings, Inc.	Manufacture pharmaceutical and medical device products		100	1300 Gould Drive Gainesville, GA, United States
Elan Holdings, Ltd.	Holding company		100	Monksland, Athlone Co. Westmeath, Ireland
Elan International Services Ltd	Financial services company		100	Clarendon House, 2 Church St Hamilton, Bermuda
Elan Management, Ltd.	Provision of management services		100	Treasury Building, Lower Grand Canal Street, Dublin 2, Ireland
Elan Pharma International, Ltd.	R&D, manufacture, sale and distribution of pharmaceutical products and financial services		100	Monksland, Athlone Co. Westmeath, Ireland
Elan Pharmaceuticals, Inc.	R&D and sale of pharmaceutical products		100	800 Gateway Blvd South San Francisco, CA, United States
Neuralab Ltd.	R&D		100	Clarendon House, 2 Church St Hamilton, Bermuda