Ten parental lines and 45 F1 hybrids of muskmelon obtained from half dialleles were studied to investigate the extent of heterosis in muskmelon. Heterotic effects over the better parent were observed to be higher for number of the node on which first female flower appeared, fruits per plant, fruit weight, fruit yield per plant, moisture content and total soluble sugars in E2 than in E1. The hybrids AMM-01-18 x AMM-02-26, Hara Madhu x RM- 50, AMM-00-25 x AMM-00-11 and AMM-01-18 x DM-1 were found to be high-yielding and heterotic in both the seasons studied and even when averaged over the two environments, with other yield attributes and quality traits. Hence, after sufficient evaluation, these hybrids were identified as potential hybrids for widespread cultivation and commercial exploitation.