Comparative morphologic, morphometric and histological studies were carried out on the cerebrum of three adult male mammalian species namely the African giant rat (Cricetomys gambianus), Rabbit (Oryctolagus cuniculus) and Wistar rat (Rattus norvegicus). The animals were acclimatized for two weeks, weighed and lightly anaesthetized with chloroform and humanly sacrificed. The brains were removed through midline incision through theskull and then fixed in Bouin's fluid,processed routinely and stained using Haematoxylin and eosin method and Special stains; Cristal violet and Silver stain. The brains were ob- served to be milky in colour and globular in shape in the three mammalian species though the size differed in the animals. The mean body weight of the African giant rat, Rabbit and Wistar rat was 1.167± 0.153kg, 1.233±0.252kg and 20.333 ±5.774g respectively. The result showed a statistical significant dif- ference between the mean body weight of the African giant rats and Wistar rats (p<0.05) and between the Rabbit and Wistar rat (p<0.05). The mean volume of the cerebrum of African giant rat, rabbit and Wistar rat was 22.967±1.620, 25.067±0.115, 11.167± 0.289 which showed a significant difference between the African giant rat and the Wistar rat and between the Rabbit and Wistar rat respectively (p<0.05). The cerebrum of the three mammalian species shows sulci and gyri but vary in their extent and sizes. The result of histological observation of the cerebral cortices shows similarities among the three species. The result showed pyramidal cell layer, plexiform layer and granular layer in the cerebrum which vary in size of the layers and cellular population. The results from the present study can be used as a baseline research data in comparative neuroanatomy for related rodent species.