To our knowledge, there have been three prior reports of patients found, with trypsin-Giemsa banding, to be monosomic for the terminal q segment of chromosome 4. Described herein is a fourth patient with this chromosome abnormality. Comparison of these four patients suggests a characteristic phenotype in the 4q- syndrome: cleft palate, satyr deformity of the pinnae, snub nose, retrognathia and micrognathia, hypertelorism, oropharyngeal hypothonia or upper airway obstruction, cardiac defect, clinodactyly of the fifth fingers with absence of a flexion crease, simian lines, displaced or clinodactylous toes, and mental retardation. In the three prior reports, the 4q- syndrome resulted from a de novo deletion. In the present case, the 4q monosomy was inherited from the father, who had a 4;20 translocation.