Introduction: The interparietal part of squamous occipital bone which lies above the highest nuchal line develops from membranous ossification. The failure of fusion of ossification centres in this region leads to the development of interparietal and pre-interparietal bones. These bones are very rare in occurrence compared to the sutural bones. In this study, the objectives were to find the incidence of interparietal and preinterparietal bones in South Indian population. Material and methods: The study included a total number of 78 human adult dried skulls of South Indian population. The skulls were studied for the gross incidence, sexual dimorphism and the number of fragments of the interparietal and preinterparietal bones. Results: From our observations, the interparietal bone was observed in only 3 skulls (3.8%) and the preinterparietal bones were observed in 8 (10.3%) skulls. The incidence rates of interparietal and preinterparietal bones were higher in females (2:1 and 5:3). The interparietal bone was single in two cases and was fragmented in the other case. The preinterparietal was single in 5 cases and fragmented in 3 cases. Conclusion: The South Indian population showed higher incidence of preinterparietal bones (10.3%) than interparietal bones (3.8%) and are more common in females. The study has provided additional information on the squamous part of occipital bone, the interparietal and preinterparietal bones, their incidence, sexual dimorphism and morphology. The knowledge of these variants is of importance to the neurosurgeons, radiologists and morphologists.