We report a case of Pallister-Killian syndrome in a 28 week gestation infant. In addition to the characteristic phenotype, this patient had a cleft palate, diaphragmatic hernia, sacral appendage, and imperforate anus. The lymphocyte karyotype showed 96% 46,XX/4% 47,XX+i (12p) and the fibroblast karyotype 47,XX,+marker (presumed i(12p]. Fibroblast cytogenetic studies should be considered in all cases of diaphragmatic hernia associated with other malformations.