The present study sought to assess the occurrence and early detection of sex-related differences for yielding ability inTelfairia occidentalis, using half-sib progenies from six diverse sources. Male plants flowered at 86 days after planting, 32 days earlier than females. Sex-related differences explained 12–43% of observed phenotypic variation for the measures of vegetable yielding ability. The strongest linkage with sex was observed for the size of the vine shoots harvested, with the effect of sex estimated at 1.29 standard deviations. There was, however, a significant heterogeneity in sex-related differences across families. Size per vine shoot and leaf yield per harvest showed early occurrence of sexual dimorphism, with sex-related differences occurring as early as 64 days after planting for size of vine shoots.