Although mutation studies are very common in most of the crop plants, soybean (Glycine max [L.] Merrill.) has received comparatively little attention by the mutation breeders. In view of this, systematic mutation studies were started at Ranchi Agriculture College, Kanke. The present study reports the effect of ganma rays on the frequency and spectrum of visible mutations in soybean. Materials and methods: Seeds of a soybean variety Sepaya Black, brought to uniform moisture content, were irradiated with ganma rays at Fertilizer Corporation of India, Sindri, Dhanbad (Bihar) at a dose of 10 kr, 20 kr, 30 kr, and 40 kr.