An ecological study on the population dynamics of rodents was carried out in thernLegedaddi Chilelo irrigated and non-irrigated agricultural field and bushland from Junern2006 to January 2007. Two trapping grids were selected randomly in the irrigated fieldrnand additional two with non-irrigated field. An additional trapping grid was selected in thernnearby bushland. A total of 166 captures were made in 3675 trap nights in live traps andrn30 individuals of small mammals were snap trapped. Mastomys natalensis (42.8%) wasrnthe most dominant species followed by Arvicanthis dembeensis (38.6%) andrnStenocephalemys albipes (18.6%). The abundance of rodent species varied among thernChilelo irrigated and non-irrigated agricultural field and bushland. There were statisticallyrnsignificant seasonal variations in the abundance of the rodent species. Similar speciesrncomposition was obtained during different seasons and habitats. All age groups werernrepresented in the population of the obtained species. There was significant variation inrntrap success among different habitat types. The diets of the rodents from the stomachrncontent analysis of snap trapped individual showed plant matter with few animal matters.rnThe density and biomass of rodents were high in the irrigated field and least in thernbushland. The density in irrigated field was 246/ha. However, the density in non-irrigatedrnfield and bushland were 72/ha and 20/ha, respectively. There was high population ofrnrodents in the first two trapping sessions.rnKey word: Irrigated field; rodents;species composition