Golabadi, M., Golkar, P. and Eghtedary, A.-R. 2015. Combining ability analysis of fruit yield and morphological traits in greenhouse cucumber (Cucumis sativus L.). Can. J. Plant Sci. 95: 377-385. Knowledge about the genetic control of the different quantitative characters related to fruit yield and its components is still insufficient in greenhouse cucumbers. This information is useful in planning breeding programs in this economically important crop. In this study, the genetics of morphological traits and fruit yield was investigated using a 9×9 full diallel population of cucumbers for the greenhouse market. Data were collected on internode length, leaf length, leaf width, fruit length, fruit diameter, number of fruits per plant, yield per fruit and yield per plant. Variance components showed that both the additive and the dominant gene effects played significant roles in the genetic control of the traits studied. Genetic control of internode length, leaf width and number of fruits per plant was accomplished by additive effects. The significant mean squares of reciprocal crosses for all of the studied traits suggested that maternal inheritance also played an important role in the inheritance of these traits. Significant general combining ability for fruit yield revealed that both selection and hybridization methods would lead to desirable genetic improvements in cucumber through accumulation of desirable alleles from parents in the target genotype, but that hybridization would be preferred.