This paper reports of study that was conducted to evaluate runoff rates and sediment yield as affected by different plant densities of amaranthus at the experimental farm of Agricultural Engineering Department, Federal University of Technology, Akure, Ondo State, Nigeria. The experimentally based study is aimed at determining the runoff and sediment yield relationship as affected by different plant densities of amaranthus at the experimental farm. Treatment were based on four plant densities A (97 plant/m2) B (42 plant/m2) C (125 plant/m2) D (69 plant/m2), runoff depths and sediment yields were measured during the months of August to November 2003. A complete randomized block design was used to evaluate treatment methods on the basis of sediment yield and run off depth. A rainfall-Runoff model was established to enable future occurrence to be predicted. The water balance equation was used to compute the evapotransipiration (ET) for each plot. There were significant differences in sediment yields and run off depths among the treatments at 5% level of significance treatment. A (97 plant/m2) and C (125 plant/m2) were found to have the least amount of runoff and sediment yield, while treatment B (42 plant/m2) and D(69 plants/m2) had the highest amount of runoff and sediment yield. The result confirms the proposition that increased plant densities had a significant effect in reducing runoff and sediment for agricultural lands.