A bomb ripped through a courtroom in Quetta during a busy Saturday morning session.
Police said a suicide bomber had caused the blast, after finding a severed head in the wreckage.
Security officials have been investigating at the scene.
The court building is in a compound which also houses police offices.
At least 15 people died in the blast.
Relatives had to face the grim task of identifying the bodies of their loved ones.
Dozens of people were injured in the blast, with several suffering serious burns.