The investigation was carried out to study the phenotypic reaction of seeds of CO 6 blackgram variety exposed to Gamma rays doses at 200 Gy, 300 Gy, 400 Gy and combination treatments with 200 Gy + 20 mM EMS, 200 Gy + 30 mM EMS, 300 Gy + 20 mM EMS, 300 Gy + 30 mM EMS, 400 Gy + 20 mM EMS, 400 Gy +30 mM EMS. It was observed that different mutation frequencies and span of mutation spectra were induced under the action of different concentrations of the applied mutagens in the M2 generation of blackgram. Five different types of chlorophyll mutants namely albino, xantha, chlorina, viridis, and maculata type were observed in the M2 populations and chlorophyll mutation frequency was calculated on a plant population basis. In Gamma treated population, the frequency of xantha mutants was high followed by chlorina whereas in combination treatments of Gamma ray + EMS, the highest frequency was observed in chlorina followed by xanthan mutants. Maculata type of chlorophyll mutant was observed in the treatment 200 Gy + 20 mM EMS. The combination treatments of Gamma ray + EMS were found to be more efficient than gamma rays alone in inducing chlorophyll mutations. The frequency of chlorophyll mutations (2.51%) was high in the combination treatment 400 Gy+ 30 mM EMS.