This paper describes for the first time the clinical findings in a case of pure trisomy (1q)(q42----qter). Eight cases involving this trisomy have been reported previously, but these were complicated by additional chromosomal changes, and hence the assignation of a discrete phenotype remained doubtful. The clinical abnormalities reported here, most of which were included amongst others in the previous reports of trisomy (1q)(q42----qter), provide the basis for characterisation of this condition as a syndrome. These changes comprised macrocephaly, prominent forehead, micrognathia, large fontanelle, flat nasal bridge, low-set ears, facial capillary naevi, cardiac defect and small size for gestational age.