A computer simulation model was used to investigate the planar dechanneling of MeV ions in diatomic diamond-type lattices. For planes consisting of an equal mixture of both atomic types, such as the (110) planes, results conform closely to those found for monatomic lattices. However, for planar directions, such as the (100), where the alternate planes consist solely of one type of atom, the dechanneling process must be analyzed in terms of the continuum potential asymmetry.