Reported is the first Japanese case of partial 2p trisomy with concomitant neuroblastoma occurring in an 8 month-old boy. The family history disclosed that his father, paternal grandfather and uncle, suffering from congenital cataract and microphthalmos, were carriers of reciprocal translocation between distal segments of the short arm of Chromosomes 2 and 16 (p13, p11). The karyotype of the patient revealed an abnormally long short arm in one of the pair of Chromosome 16 that was similar to the change of Chromosome 16 found in his father and the other paternal members of his family, while Chromosome 2 appeared normal. Subsequently the patient was interpreted to be trisomic for many distal segments of 2p and monosomic for almost entire segments of 16p. Clinical features of the present case demonstrated many characteristics common to those of the reported cases of partial 2p trisomy syndrome in foreign countries. Relation of this rare chromosomal abnormality to the concomitant occurrence of neuroblastoma was briefly discussed.