OHO were formed in 1973 in Baltimore as a trio: guitarist Joe O'Sullivan, keyboardist Mark O'Connor, and bassist Steve Heck. The name of the band is the initials of their last names. Heck left and two brothers (guitarist Jay Graboski and drummer Jeff Graboski) joined for their debut album Okinawa (1974), a chaotic work of prog-rock and acid-rock inspired by Frank Zappa and Captain Beefheart. O'Connor and the Graboski brothers played on Damaged Goods' EP The Dark Side (1979).

They resurfaced during the New Wave with the EP Rocktronics (1984) and the album Audition (1989). By the time Oho (1990) came out, they had turned to folk-rock with two female singers. Grace Hearn sounds like Kate Bush. The garage rave-up of Scared Money and the ballad Till Death Do Us Part are the highlights.

Old recordings were collected on Vitamin Oho (1991) and Ecce Oho (1998).

After a long hiatus, OHO returned with Up (2005), Bricolage (2008) , Gazebo (2018) and Ahora (2022).