WXDX-FM (105.9 MHz) is a commercial radio station that is located in Pittsburgh, Pennsylvania. Known as 105.9 The X, it airs an alternative rock radio format and is owned by iHeartMedia. Its studios and offices are located on Abele Road in Bridgeville next to I-79. WXDX is the flagship radio station of the Pittsburgh Penguins hockey team.

WXDX-FM has an effective radiated power (ERP) of 15,500 watts. Its transmitter is located off Swanson Street in Pittsburgh's North Side, on a tower shared with KDKA-TV and other FM stations. WXDX-FM broadcasts using HD Radio technology.

On January 1, 1961, the station signed on as WAZZ and later as WAMO-FM. At first, its effective radiated power was 4,500 watts but it later had the most powerful FM signal coverage in Western Pennsylvania, broadcasting with 72,000 watts. It initially simulcast the same programming as its AM sister station, WAMO (now WAOB). WAMO-AM-FM served the Pittsburgh African-American community with R&B and soul music, as well as Black talk and news programming on weekdays, and religious shows on Sundays.

In the later 1960s, the FM station began separate programming, specializing in Urban contemporary music, with WAMO-AM-FM sometimes simulcasting on weekends. Over the years, the station was branded as Hot 106 WAMO.

It also had various formats during its later years, which also included Disco music and Rhythmic Contemporary or "CHUrban".

On April 10, 1996, at 3 p.m., WAMO-FM swapped frequencies with WXDX-FM, with the urban format moving to 106.7 FM, while WXDX's alternative rock format moved to the more powerful 105.9 FM frequency.

WXDX-FM was one of six stations owned by Clear Channel Communications (now iHeartMedia) that dropped The Howard Stern Show in February 2004 (however, Stern would show up on WRKZ later that year). Howard began airing on WXDX in November 1995 (when it was still on 106.7 FM).

Since 2008, WXDX-FM has served as the home for sports talk host Mark Madden.