Exhibit 99.1

VIA UNITED PARCEL SERVICE

SIGNATURE REQUIRED

May 25, 2017

Mr. Joe Kiani, Chief Executive Officer

Masimo Corporation

52 Discovery

Irvine, CA 92618

Dear Mr. Kiani:

The Food and Drug Administration has completed an evaluation of your corrective actions in response to our Warning Letter (WL#31-14), dated 08/12/14. Based on our evaluation, it appears that you have addressed the violations(s) contained in this Warning Letter. Future FDA inspections and regulatory activities will further assess the adequacy and sustainability of theses corrections.

This letter does not relieve you or your firm from the responsibility of taking all necessary steps to assure sustained compliance with the Federal Food, Drug, and Cosmetic Act and its implementing regulations or with other relevant legal authority. The Agency expects you and your firm to maintain compliance and will continue to monitor your state of compliance. This letter will not preclude any future regulatory action should violations be observed during a subsequent inspection or through other means.

Sincerely,

Kelly D. Sheppard

Acting Program Division Director

Division3/West

Office of Medical Device and Radiological Health Operations

KS:rwb

U.S. Food and Drug Adminstration

OMDRHO Division 3/West

19701 Fairchild Road

Los Angeles, CA 92612

www.fda.gov