The study was conducted to evaluate economics of soyabean production under Sasakawa Global 2000 project in Kaduna State, Nigeria. The specific objectives of the study were to describe the relevant socio-economic characteristics of soya bean producers under SG 2000 Project, analyse costs and returns to soya bean production under SG 2000 Project, examine the relationship between inputs and output of the project's soya bean farmers, determine the technical, allocative and economic efficiencies as well as evaluate the determinants of inefficiencies in soya bean production among SG 2000 participating farmers, and identify the challenges encountered by SG 2000 Project soya bean farmers in the study area. A purposive sampling technique was used to select 107 Sasakawa maize farmers. Primary data were collected with the aid of structured questionnaire. The data were analysed using descriptive statistics, gross margin analysis and stochastic frontier function. The results showed that the mean age of the farmers was 49 years. Majority of respondents (89%) were literate and most of them (78%) cultivate on small scale farms (0.1-1.0ha) and 62% had access to credit facilities while 74% were not members of any cooperative group. Soya bean production under sasakawa project was found to be profitable as a gross margin of N240,952/ha was achieved. The mean efficiencies were 89%, 73% and 65% for technical, allocative and economic efficiencies hence; there is room for improvement of the farmers' efficiencies to increase outputs. Farm size, quantity of seeds and quantity of fertilizer had positive effects on both technical and economic efficiencies just as costs of farmland, seeds, fertilizer, agrochemicals, labour and output were seen to have positive effects on allocative efficiency. Determinants of inefficiencies of the farmers were educational level, household size, farming experience, amount of credit received and membership of cooperative organization. Major constraints encountered by the farmers were insufficient credit, inadequate land, absence of threshing machines and equipment, bad roads and inadequate labour. It was therefore recommended that inputs such as seeds, fertilizers and agrochemicals which were the major inputs that increase the output of soya bean production in the study area should be made available on time, in right amounts and at affordable prices to the farmers by SG 2000 project and other stakeholders in agriculture. Participating SG 2000 farmers should be encouraged to form themselves into cooperative groups in order to enhance their accessibility to interventions and subsidies provided by the project and other stakeholders as well.