Grain legumes have great potential for improving smallholder farmers’ productivity in SubSaharan Africa (SSA). However, this has not been fully exploited due to critical problems such as high insect pests and disease infestation. As part of addressing these challenges, Kenya Agricultural and Livestock Research Organization (KALRO) in collaboration with Cornell University and supported by the Collaborative Crop Research Program (CCRP) introduced crop and soil enhancing strategies in Western Kenya. One of the strategies included use of multipurpose grain legumes species in Nandi County. Through this initiative, various legume species including common bean, cowpea, groundnuts, dolichos lablab and soybean are being promoted at the farm level. However, the extent of their utilization and the actual benefit is not known precisely as it is not comprehensively documented. Furthermore, no empirical study has delved in the assessment of the economic benefits that farmers are likely to obtain if they adopt the legume species. In order to address the aforementioned knowledge gaps, the present study sought to analyze utilization and evaluate gross margins of grain legumes. Data was collected from a random sample of 163 farmers from three study sites in Nandi County (Koibem, Kapkerer and Kiptaruswo sites). Descriptive statistics on frequencies and percentages on utilization and legume attributes were presented in graphs and tables. Further, gross margins were computed from farm-level data while multiple regression model was applied to determine factors influencing the gross margins obtained. Results showed that farmers’ priorities for use of legume included; food dishes, income generation, forage and soil fertility improvement. This indicates that farmers value legumes for home consumption purposes and also for income. Descriptive statistics revealed that about 56 percent of the households had positive gross margins while the rest incured losses in the production of grain. Further, beans, groundnuts, cowpeas and soybean had positive gross margins while dolichos lablab gross margin was negative. This indicates that vi generally legumes farming is feasible. Groundnuts and beans accounted for about 49 percent and 36 percent, respectively of the total legume gross margins. Farm labour cost was the largest component of cost, accounting for about 68 percent of the total variable production cost of legumes. An analysis of variance (ANOVA) showed that there was no statistical difference at 95 percent in the mean gross margins for the legumes studied. Further, the multiple regressions indicated that area under grain legumes, age of the farmer, access to extension services and access to credit had significant influence on gross margin. As such, different interventions are needed so as to promote the production and diversify utilization patterns of the legumes. For instance, interventions geared towards increasing diversification of utilization of legumes through processing and value addition by for instance processor village groups for soybean or any other legume through provision of processing equipment and training on the usage by the project is necessary. Also, there is need to minimize labour cost for instance through provision of seeds with less labour requirements to farmers. Further, there is the need for appraisals of extension services in order to improve the delivery to farmers. Similarly, policies and interventions which can promote credit access would enhance gains from legumes.