The blast came as the minority Shia community prepared to mark this weekend's Ashura festival.
An eyewitness told the BBC the teenage bomber pushed past security personnel before blowing himself up.
Security has been high in Pakistan during the holy month of Muharram, of which Ashura marks the climax.
A BBC reporter at the scene counted five bodies and was told by officials other dead had been removed.
Thursday's bombing happened in the same area of Peshawar where 11 people died in a suicide attack last year during Ashura.
This a list of 25 suicide attacks in NWFP during 2007. Click here