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 * Rust Scott Arthur   2. Issuer Name and Ticker or Trading Symbol NATIONAL INSTRUMENTS CORP [NATI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Senior Vice President (Last) (First) (Middle) C/O NATIONAL INSTRUMENTS CORPORATION, 11500 NORTH MOPAC 3. Date of Earliest Transaction (Month/Day/Year) 02/01/2019 (Street) AUSTIN, TX 78759 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 02/01/2019   M V 199 (1) A $ 37.587 36,274 D   Common Stock 05/01/2019   M V 154 (1) A $ 37.587 36,428 D   Common Stock 05/01/2019   M   11,326 A (2) 47,754 D   Common Stock 05/01/2019   F   4,068 D $ 43.4716 43,686 D

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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	(2)	05/01/2019		M			851	(3)	05/01/2026	Common Stock	851	$ 0	808	D
Restricted Stock Units	(2)	05/01/2019		M			794	(3)	05/01/2027	Common Stock	794	$ 0	1,715	D
Restricted Stock Units	(2)	05/01/2019		M			510	(3)	05/01/2028	Common Stock	510	$ 0	1,625	D
Restricted Stock Units	(2)	05/01/2019		M			567	(3)	05/01/2029	Common Stock	567	$ 0	2,316	D
Restricted Stock Units	(2)	05/01/2019		M			1,701	(3)	05/01/2030	Common Stock	1,701	$ 0	8,639	D
Restricted Stock Units	(2)	05/01/2019		M			1,903	(3)	05/01/2031	Common Stock	1,903	$ 0	9,776	D
Restricted Stock Units	(2)	05/01/2019		M			5,000	(4)	05/01/2032	Common Stock	5,000	$ 0	10,000	D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Rust Scott Arthur C/O NATIONAL INSTRUMENTS CORPORATION 11500 NORTH MOPAC AUSTIN, TX 78759			Senior Vice President

Signatures

R. Eddie Dixon, Jr. as attorney-in-fact for Scott Arthur Rust		05/02/2019
**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)	Acquisition of stock under Issuer's employee stock purchase plan.
(2)	Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.
(3)	The restricted stock units vest and become exercisable based on time and performance milestones set by the Issuer.
(4)	The restricted stock units vest in four equal annual installments on the anniversary of the vesting commencement date of May 1, 2017.

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