Dearth of information exists on the effects of planting dates and genotypes on grasshopper (Zonocerus variegatus L.) infestation and dry matter accumulation in the root organ of cassava. An experiment was conducted at the School of Agriculture and Food Sciences Experimental site of Njala University site during 2007/2008 and 2015/2016 cropping seasons. This study assessed the effects of planting date and cassava genotypes on grasshopper infestation and root dry matter accumulation in cassava. The experiment utilized four cassava genotypes (Cocoa, SLICASS 1, SLICASS 4 and SLICASS 6) and three planting dates (June, September and December) laid out in a Randomized Complete Block Design (RCBD) with three replications. Findings showed that the incidence and severity of grasshopper attacks, as well as root dry matter contents were significantly (p<0.05) different between variety and planting...