This song was written by guitarist Glenn Tipton, and was a live staple from its release up to 1980, and also during 2001-2002 when Tim "Ripper" Owens was in as lead singer, replacing Rob Halford, who returned in 2003. Halford has also performed the song with his solo band.
"Running Wild" has a lot of Judas Priest hallmarks, including a twin-guitar attack from Tipton and KK Downing, and a lyric about living with unbridled abandon. Its propulsive energy made it a great live track.
The band wrote this in the studio at a time when they were crazy busy but united in their ambitions. After wrapping up their Stained Class tour in August 1978 with five shows in Japan, they returned home and got right to work on their next album, which included "Running Wild" and was called Killing Machine everywhere but America, where their record company didn't want it associated with recent school shootings. There, the album was called Hell Bent For Leather, named after one of the tracks. This worked out pretty well for them when American fans adopted that phrase as a kind of credo for Judas Priest, which was the first metal act to outfit themselves in leather and studs.
Some have accused Iron Maiden of stealing the song's riff and using it for their 2000 track "The Wicker Man."
The German heavy metal band Running Wild took their name from this song.