The dataset represents 501 mammal records. This include 213 occurrence records of mammal species recorded in a field expedition undertaken in mid Tana River Basin (TRB) ecosystem (Bangal, Garissa, Bura and Hola), in between 1st to 7th November 2019. A total of 38 different small and medium sized mammal species of 11 orders were recorded from above expedition. Order Cetartiodactyla (Even-toed Ungulates), Carnivora (Carnivorans) and Primates (Primates) were the most common. Of the 213 mammal observations counted in the entire