Estimates of heterosis were obtained for 10 characters in 45 hybrids of Indian mustard (Brassica juncea L. Czern & Coss). Manifestation of heterosis was of high order for number of primary branches, number of secondary branches, number of siliquae per plant, biological yield per plant, harvest index, 1000-seed weight and seed yield per plant. The range of heterosis was quite low for days to flower and days to maturity. A large number of crosses exhibited significant negative heterosis for days to maturity. For seed yield, Pusa Bahar x Pusa Basant recorded highest standard heterosis of 28.04 percent. In general, crosses involving at least one of the parents with high performance yielded heterotic results. However standard heterosis exhibited by Pusa Bahar x Pusa Basant indicates manifestation of heterosis even when both the parents are low performing.