A boy with microcephaly, unusual facial features, micropenis, and growth retardation was born to a 30-year-old woman who took azathioprine and prednisone before and during pregnancy for systemic lupus erythematosus. The child has two apparently de novo chromosomal abnormalities: an apparently balanced translocation between chromosomes 6 and 14 and an interstitial deletion of chromosome 7. The karyotype is 46,XY,del(7)(q21);t(6;14)(q21;q12). Use of azathioprine and prednisone in pregnancy has been associated with intrauterine growth retardation, congenital malformations, and transient chromosome breaks in the blood of newborns. To our knowledge, this is the first report of de novo constitutional chromosome abnormalities in such an infant. We suggest that the assessment of infants born to parents treated with azathioprine should include a chromosome study, even if the infants seem to be normal.