MONOLITHIC POWER SYSTEMS INC — Director's Dealing 2011

May 2, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
Period of Report: 2011-05-02

Reporting Person: Sciammas Maurice (Sr. V.P.of Sales and Marketing)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-02	Common Stock	S	885	$17.1508	Disposed	91509	Indirect
2011-05-02	Common Stock	S	350	$17.1508	Disposed	22921	Indirect
2011-05-02	Common Stock	S	350	$17.1508	Disposed	22921	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	118901	Direct

Footnotes

F1: In accordance with the reporting person's 10b5-1 trading plan.

F2: The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $17.02 to $17.27. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

F3: Shares held by Sciammas Family Living Trust, Maurice Sciammas and Christina Sciammas, Trustees

F4: Shares held by Christina Sciammas 2004 Trust, Christina Sciammas and Maurice Sciammas, Trustees

F5: Shares held by Maurice Sciammas 2004 Trust, Maurice Sciammas and Christina Sciammas, Trustees