In present investigation 54 genotypes (10 lines + 4 testers + 40 F1's) of sponge gourd was conducted in Randomized Block Design with three replications to know the gene effects with respect to its nature and magnitude for growth, yield and its contributing characters. Combining ability analysis elucidated higher magnitude of variances due to SCA (?2s) than variance due to GCA (?2g) indicating preponderance of non-additive gene action for almost characters. The values of dominance genetic variance (?2D) higher than additive genetic variance (?2A) and as a consequence average degree of dominance were more than unity (>1) for all the characters under study except for days to anthesis of first staminate flower, days to anthesis of first pistillate flower, days to first fruit harvest, number of primary branches per plant, inter nodal length, fruit length and fruit circumference in both the years which indicated existence of dominance gene effects for these traits. Days to anthesis of first staminate flower, days to anthesis of first pistillate flower, days to first fruit harvest, number of primary branches per plant, inter nodal length, fruit length, fruit circumference and number of fruits per plant which had less than one value of average degree of dominance suggested existence of partial dominance. The predictability ratio was lesser than (<1) for all the characters under study in both the years except fruit circumference in case of Y1. High estimate of heritability in narrow-sense was recorded for all fourteen traits in both the years and high estimate of genetic advance in per cent of mean (>20%) was observed for average fruit weight in Y1 along with moderate estimate of genetic advance in per cent of mean was observed for average fruit weight in Y2. These results clearly indicates that non-additive gene action were in preponderance practice of exploration of hybrid vigor in sponge gourd.