Tension pneumocephalus has been reported frequently after posterior fossa surgery, mostly in procedures done in the sitting position. Though uncommon, tension pneumocephalus is a life-threatening complication that requires urgent diagnosis and treatment. It is rare for this complication to occur after neurosurgical procedures done in the supine position. The authors report a case of an adult patient diagnosed with craniopharyngioma who developed tension pneumocephalus following craniotomy in the supine position.