Half-diallel was obtained from four genet:ically divers lines of cucumber. General (GCA) and specific (SCA) combining ability was estimated for days to flowering, number of pistillate flowers, number of fruits per plant and main stem length (plant height) . GCA-effects of the parents (additive effects) were more sensitive by the changes of treatments (planting seasons) for all traits except of female flowering time. Line 1909 was the best combiner for early female flowering and number of female flowers per plant. ':'he genotype "Chinese long" was the best combiner in open field for number of fruits per plant and plant height, while the line 1909 was the best combiner under green house conditions as well as for fruits per plant and plant height.