WMSW
City of license	Hatillo, Puerto Rico
Branding	Radio Once
Frequency	1120 kHz
First air date	December 24, 1980
Format	News/Talk
Power	2,600 watts (day) 5,000 watts (night)
Class	B
Facility ID	3257
Transmitter coordinates	18°28′15″N 66°50′24″W
Owner	Aurora Broadcasting Corporation
Website	http://www.radioonce.com/

WMSW (1120 AM, "Radio Once") is a radio station licensed to serve Hatillo, Puerto Rico. The station is owned by Aurora Broadcasting Corporation.[1] It airs a News/Talk format.[2]

The station was assigned the WMSW call letters by the Federal Communications Commission on December 31, 1979.[3]