Study of heterosis in 29 different hybrids of mungbean. resulting from 8 x 8 diallel, excluding reciprocals indicated pronounced hybrid vigour for yield and most of the yield components. Heterosis to the extent of 110.77 and 77.54% over the mid parent and better parent, respectively, was recorded for grain yield per plant. Heterosis for yield was generally accompanied by heterosis for yield components. Eight hybrids were identified as promosing for many desirable traits and they may be of much use in exploiting hybrid vigour in mungbean.