MONOLITHIC POWER SYSTEMS INC — Director's Dealing 2011

May 31, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
Period of Report: 2011-05-31

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-31	Common Stock	S	885	$17.0715	Disposed	87969	Indirect
2011-05-31	Common Stock	S	350	$17.0715	Disposed	21521	Indirect
2011-05-31	Common Stock	S	350	$17.0715	Disposed	21521	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	115658	Direct

Footnotes

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

F2: Shares held by Sciammas Family Living Trust, Maurice Sciammas and Christina Sciammas, Trustees

F3: Shares held by Christina Sciammas 2004 Trust, Christina Sciammas and Maurice Sciammas, Trustees

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