Abstract: Background and Objective: Protein deficiency is considered as the commonest form of malnutrition in the developing countries. Phaseolus lunatus seed is an important source of vegetable protein and is highly underutilized in the country despite its great potential. Proximate, mineral and anti-nutrient composition of Phaseolus lunatus seeds, treated with varying concentration of mutagens were investigated. Materials and Methods: Seeds were treated with fast neutron irradiation from Americium Beryllium source (241Am/Be), colchicine by soaking in freshly prepared concentration of Colchicine 0.2 mM for 6 h and ethyl methane sulphonate by soaking in freshly diluted concentration of EMS (0.1%) for 6 h. Treated seeds were sown and harvested after two months. Harvested seeds were analyzed and tested for their proximate, minerals and anti-nutrient composition following standard procedures. Results: The mutagens significantly (p<0.05) affected all proximate composition except crude fibre and ash contents. Anti-nutrients varied significantly (p<0.05) except tannin which ranges from 2.08-2.84 mg g–1. All mineral contents also varied significantly (p<0.05) except potassium. Conclusion: Phaseolus lunatus seeds can serve as an alternative to common legumes for protein supplement and mutagens can be used to improve their nutrient quality.