Clinical descriptions of individuals with partial deletion of the distal short arm of chromosome three have been reported rarely. A characteristic phenotype has been proposed. We present another patient with this cytogenetic abnormality whose physical and developmental features show similarities with, as well as differences from, previously reported cases. This suggests that the clinical phenotype requires further definition. In addition, gene dosage studies were undertaken on several serum proteins in order to try to map the location of the responsible genes on chromosome three.