Sacrum of guinea pig was triangular in shape. Sacrum was formed by fusion of four and three sacral vertebrae in male and female guinea pigs respectively. Adorsal sacral and two lateral sacral crests were present on the dorsal surface of sacrum. Wings presented an articular area in the lower part of its lateral aspect for the ilium. Anterior articular processes were present and faced upwards. Slender transverse processes were two at the caudal part of sacrum and projected backwards. Sacral spinal canal had a cranial triangular opening whereas posteriorly resembled an aperture. The number of dorsal and ventral sacral foramina differed in both the sexes. The morphometric measurements namely, length and width of sacrum were measured.