A real defect structure is studied for ZnGeP2 crystals grown by the vertical Bridgman technique from the melt. Optical microscopy reveals growth striations and precipitation of second phases emerging because of deviation from stoichiometry. The revealed growth striae have a complex structure caused by temperature oscillations in the growth setup. The other type of defect, precipitates. is observed as a colony of trails orienting in the longitudinal direction. The colony of trails occurs with a concave interface and as a rule, is located in the central part of the lateral section of crystal. The most probable composition of the precipitates is a mixture of ZnGeP2, Zn3P2, and Ge. The colony of the precipitate trails results in significant optical losses over the whole transparency range of ZnGeP2. (C) 2002 Elsevier Science B.V. All rights reserved.