Study of heterosis in 42 different hybrids of mungbean resulting from 7 x 7 complete diallel. including redprocals indicated a pronounced hybrid vigour for yield and most of the yield components. Heterosis to the extent of 58.74 (D), 47.48(R) and 52.65(D), 41.82(R) % over the mid parent and better parent respectively. was recorded for grain yield per plant Crosses between high x high and high x low gca parents exhibited greater heterosis. PMB 27 and ML 713 were promising parents parents which showed high heterosis for seed yield per plant and number of pods per plant. Four hybrids were identified as promising for many desirable traits and they may be of much use in exploiting hybrid vigour in mungbean.