A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN AGRICULTURAL ECONOMICS OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Paddy and sugarcane are important food and commercial crops in Tanzania. Paddy and sugarcane have similar ecological requirements. In areas where both are produced the two crops compete for resources. Therefore better decisions have to be made on land allocation so that farm profitability can be maximized. Unfortunately the knowledge on appropriate land allocation for paddy and sugarcane enterprises is limited in the literature. Thus the present study was conducted in Kilombero district to determine profitability of paddy and sugarcane produced by smallholder farmers and the profit maximizing combination of the two crops. Specifically the study aimed at comparing the returns to land for paddy and sugarcane enterprises, determining the most profitable combination for paddy and sugarcane enterprises and identifying constraints in paddy and sugarcane production and marketing. Primary data were collected through a cross-sectional survey by using structured questionnaires. A total of 138 smallholder farmers who produce both paddy and sugarcane were randomly selected and interviewed. Smallholder farmers in the study area were found to use acreage as their unit of land. By using gross margin analysis sugarcane was found to have high return to land per acreage than paddy. Hence sugarcane is more profitable than paddy. But it was found that Kilombero Sugar Company which is the only market for sugarcane in Kilombero district has low processing capacity. The company cannot buy all sugarcane produced by smallholder farmers per year. By using linear programming model the study found that, for a smallholder farmer to maximize farm profitability per year it is better to cultivate 4 acres of paddy and 2.5 acres of sugarcane. Many other constraints were identified but the study concludes that the market limit for sugarcane is the major constraint for smallholder farmers to maximize their farm profits. The study recommends more investment in sugarcane processing.Innovative Agricultural Research Initiative (iAGRI)