Using their own experience which they described in 1984 and reviewing as well the literature of the condition since that time has led the authors to suggest that triploidy should be considered as a pathological entity with three clinical forms: early abortion, mid-trimester termination and the birth of triploidy fetuses either alive or dead. They discuss the clinical features, the ultrasound appearances, the pathological and anatomical details and the cytogenetics of triploidy. They differentiate this condition from trophoblast disease and from the central hydropic conditions which occur with normal caryotypes. They emphasize that there is a difference in the way classical molar pregnancy evolves and repeat again that the term "embryonic mole" should be avoided.