WJMN (94.5 FM) is a rhythmic CHR radio station licensed to Boston, Massachusetts, United States, and is owned and operated by iHeartMedia.

In 1965, to comply with a Federal Communications Commission regulation limiting simulcasting between commonly owned AM and FM stations in the same city, WHDH-FM began separate programming with an automated middle-of-the-road format in stereo.

In late 1967, WHDH-FM changed its format to automated progressive rock (predating future FM rocker WBCN by several months), but by late 1969, the station returned to automated beautiful music after a little "intervention", allegedly from WHDH Inc.'s chief executive officer, Harold J. Clancy (who did not particularly approve of putting rock and roll on "MY FM station!").

By the end of 1975, WCOZ had live announcers around the clock that also included George Taylor Morris, Leslie Palmiter, Lisa Karlin, Mark Parenteau and Robert Desiderio.

Program director David Gariano had success with the Top 40 format, which featured original 1984 personalities Mike Morin and Brad Krantz, Jeff Michaels, Steve York, Jim Cutler, Uncle Johnny, Jon "Rock N Roll" Anthony, Marc Mitchell, and Scott Brunner.

[9] When "Jam'n" debuted, the station had a playlist of a balanced mix of R&B/hip-hop, rhythmic pop, and dance product (the same approach was used at WXKS-FM when it made the transition from disco to urban in 1981, and then to Top 40 the following year).

This would last until the beginning of 2009, when WJMN began tweaking their musical selection to once again include rhythmic/pop-charting artists like Britney Spears, Justin Bieber, Kesha, Katy Perry, David Guetta, Edward Maya, Adele, and Lady Gaga.

This tweaking has sparked a lot of talk on radio message boards[10] and follows a pattern among rhythmic-format stations that have scaled back on the heavy amount of hip-hop in favor of a more balanced approach.

Because of this, several music trades (like Mediabase) and Nielsen Audio have listed WJMN as Rhythmic because the audience it targets is racially mixed and the region's African-American population is not that large.

[19] It also previously broadcast old-school hip hop music from January 27, 2006, to March 1, 2013, and offered a simulcast of sister station WXKS from then until November 2018.