Mutation has been successfully employed in breeding of several food crop varieties, ornamentals and export crops. The aim of this study was undertaken to assess the effectiveness and efficiency of EMS and gamma rays on Lablab purpureus (L.) Sweet var. typicus cv. CO(Gb)14. Genetically pure, uniform and dry seeds were treated with different doses/ concentrations of gamma rays (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 KR) and EMS (5mM, 10mM, 15mM, 20mM, 25mM, 30mM, 35mM, 40mM, 45mM and 50mM). Mutagenic effectiveness and efficiency of gamma rays and EMS was calculated on the biological damage (lethality, injury and pollen sterility) in the M 1 generation and both chlorophyll and morphological mutations observed in the M 2 generation. The results indicated that, mutagenic effectiveness and efficiency decreased with increase in mutagenic treatments.