MASIMO CORP — Director's Dealing 2011

May 4, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MASIMO CORP (MASI)
CIK: 0000937556
Period of Report: 2011-05-02

Reporting Person: Paul Stephen E. (EVP, Acute Care Sales)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-02	Common Stock	S	9000	$35.00	Disposed	0	Direct
2011-05-02	Common Stock	M	1000	$24.68	Acquired	9000	Direct
2011-05-02	Common Stock	M	2000	$23.14	Acquired	8000	Direct
2011-05-02	Common Stock	M	6000	$28.50	Acquired	6000	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-05-02	Non-Qualified Stock Option (Right to buy)	$24.68	M	1000	Disposed	2019-08-17	Common Stock (1000)	Direct
2011-05-02	Non-Qualified Stock Option (Right to buy)	$23.14	M	2000	Disposed	2019-03-04	Common Stock (2000)	Direct
2011-05-02	Non-Qualified Stock Option (Right to buy)	$28.50	M	6000	Disposed	2018-03-17	Common Stock (6000)	Direct

Footnotes

F1: The shares covered by this Form 4 have been sold pursuant to a Rule 10b5-1 Sales Plan dated December 17, 2010, which is intended to comply with Rule 10b5-1 promulgated under the Securities Exchange Act of 1934, as amended.

F2: This option was granted on August 17, 2009 and is exercisable as the option vests. This option vests over a five year period, with 20% of the shares subject to the option vesting on each anniversary of the grant date.

F3: This option was granted on March 4, 2009 and is exercisable as the option vests. This option vests over a five year period, with 20% of the shares subject to the option vesting on each anniversary of the grant date.

F4: This option was granted on March 17, 2008 and is exercisable as the option vests. This option vests over a five year period, with 20% of the shares subject to the option vesting on each anniversary of the grant date.