FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * KIANI JOE E   2. Issuer Name and Ticker or Trading Symbol MASIMO CORP [MASI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) CEO and Chairman of the Board (Last) (First) (Middle) C/O MASIMO CORPORATION, 52 DISCOVERY 3. Date of Earliest Transaction (Month/Day/Year) 01/02/2019 (Street) IRVINE, CA 92618 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 01/02/2019   M   20,000 A $ 0 149,241 D   Common Stock 01/02/2019   S   5 D $ 93.42 (1) 10,368 I See Footnote (2) Common Stock               229,290 I By Trust (3) Common Stock               550,000 I By Trust (3) Common Stock               352,919 I By Trust (3) Common Stock               359,000 I By Trust (3) Common Stock               2,250,291 I By Trust (4) Common Stock               9,000 I See Footnote (5)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Units

(6)

01/02/2019

M

20,000

(7)

(7)

Common Stock

20,000

$ 0

60,000

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
KIANI JOE E C/O MASIMO CORPORATION 52 DISCOVERY IRVINE, CA 92618	X		CEO and Chairman of the Board

Signatures

/s/ David J. Van Ramshorst, Attorney-In-Fact		01/04/2019
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	During fiscal year 2018, the administrator of the Masimo Retirement Savings Plan liquidated on a quarterly basis a nominal amount of Masimo Corporation shares as payment of quarterly administration fees. The liquidation of shares is reflected in this Form 4 filing. The average sales price reflected in box 4 above is an average of the quarterly sales of these shares. The information reported in this filing is based on a plan statement dated December 29, 2018.
(2)	Shares held in Masimo Retirement Savings Plan.
(3)	Shares held in four trusts for which Mr. Kiani is not the Trustee.
(4)	Shares held in one trust for which Mr. Kiani is the sole trustee.
(5)	Shares held by an immediate family member for which Mr. Kiani exercises voting and investment control.
(6)	Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of the Issuer upon vesting of the RSU.
(7)	On February 27, 2018, the Reporting Person was granted 100,000 restricted stock units, 20% of which vested upon grant and 20% of which will vest on the first business day of each fiscal year thereafter.

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