A New species of marsupial frog, Gastrotheca, with prominent cranial crests is described from humid montane forest on the eastern slopes of the Andes in Departmento de Pasco, Peru. The frog ahs an exceedingly robust cranium that most closely resembles that of G. cornuta; however, the cranial crests of G. cornuta are less well developed, and less obvious externally, than those of the new taxon. Within the genus Gastrotheca, one of the most variable parts of the skull is the squamosal, which has a variety of articular arrangements with the maxilla, the pterygoid, and in some taxa, the frontoparietal. In contrast to the modifications of dermal cranial elements, the postcranial skeleton seems to be relatively conserved in Gastrotheca.