Full text article. Also available at https://doi.org/10.5539/enrr.v9n3p41The need for rapid development in developing countries has led to establishment of major public infrastructure even in biodiversity rich protected areas. Mikumi National Park in central Tanzania is traversed by five such major infrastructures namely an optic fibre, a busy public road, an oil pipeline, power lines and railways. We assessed diversity and abundance of small terrestrial mammals of the order Eulipotyphla and Rodentia as indicator groups in relation to impacts of such infrastructure. Animals were live trapped during wet (February-April) and dry (July- September) seasons in 2018 from three established plots along the three transects set perpendicular to each of the four infrastructures. In 10102 trap nights, we captured 453 small mammals of nine species of which Mastomys natalensis constituted 75.4 % of total catch. Diversity and abundance varied between seasons, infrastructure and plots location. Dry season had significantly higher diversity than wet season and the railway site had higher diversity than the other infrastructure. The intermediate plots (500 m from infrastructure) had significantly higher abundance of animals than immediate (0-50 m) and distant (1000 m) plots. The differences in these results can be attributed by seasonal fluctuations of animal populations, and intensity of disturbance in each infrastructure and plot. It is important to examine impacts of future infrastructure developments using small mammals.