MONOLITHIC POWER SYSTEMS INC — Director's Dealing 2011

May 3, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
Period of Report: 2011-05-03

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-03	Common Stock	S	233	$16.5703	Disposed	118668	Direct
2011-05-03	Common Stock	S	1135	$16.5702	Disposed	117533	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	91509	Indirect
Common Stock	22921	Indirect
Common Stock	22921	Indirect

Footnotes

F1: Shares sold to pay tax obligations resulting from the vesting of restricted stock units.

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