A newborn with severely shortened ribs, short limbs, and postaxial polydactyly died shortly after birth. Postmortem roentgenograms established the diagnosis of type 3 short rib-polydactyly (SRP) syndrome as described by Naumoff and associates. Histopathologic study showed the chondrocytes to contain previously undescribed cytoplasmic inclusion bodies that were PAS-positive and diastase-resistant. The material appeared by staining reactions to be a glycoprotein that was seen electron microscopically to accumulate within dilated cisterns of rough endoplasmic reticulum. Similar cytoplasmic inclusions have not been seen in other short rib-polydactyly syndromes, including SRP types 1 and 2, Jeune syndrome, and Ellis-van Creveld syndrome. It is often difficult to differentiate cases of type 3 and type 1 (Saldino-Noonan) syndrome, and in the past the diagnosis has sometimes been confused. A review of previously reported cases showed that type 3 syndrome rarely (1 in 13) had cloacal developmental abnormalities, which are invariably present in patients with type 1 syndrome. Type 3 is also associated with a lower incidence of congenital heart disease, and cardiac malformations, when present, differ from those associated with type 1 syndrome. Both type 3 and type type 1 SRP syndromes are transmitted in autosomal recessive fashion. Type 3 SRP syndrome has had an equal sex distribution, although type 1 has so far been reported to occur only in girls. Further investigation with additional patients is necessary to verify the above preliminary findings.