The 3p- syndrome (terminal deletion of the short arm of chromosome 3 with breakpoint at 3p25) was found in the G-banded karyotypes from an undergrown and developmentally retarded 13-month-old girl with a distinct pattern of congenital abnormalities. Features present in the patient and characteristic of the 3p- syndrome included low birthweight, brachy-trigonocephaly, a high and narrow forehead with a prominent metopic suture, epicanthic folds, upslanting palpebral fissures, ptosis, depressed nasal bridge, anteverted nares and a small mandible. She lacked postaxial polydactyly of fingers and toes which is present in about half of the so far reported about one dozen 3p- cases, but she showed an anteriorly placed anus. The deletion was overlooked at a first routine cytogenetic examination. At a later clinical evaluation of the patient, the suspicion of the 3p- syndrome was raised and the aberration found at revision of the old karyotypes. The importance of a good information flow between clinicians and cytogeneticists is stressed.