We describe a patient who had multiple malformations including ventriculomegaly, colpocephaly, corpus callosum, cerebellum and vermix hypoplasia, optic nerve hypoplasia, corneal opacity and congenital heart disease in whom a trisomy 1q32-qter and monosomy 5p derived from a t(1;5)mat was diagnosed by karyotype and FISH analysis. This trisomy/monosomy association has not been previously reported. The familial analysis of the translocation was carried out in four generations and its implications on the phenotype of the patient and genetic counseling are discussed.