A complete diallel cross study of three local populations (Ahmet, Dalli and Iri) and one cultivar (Çakmak-79) of durum wheat (Triticum durum Desf.) was carried out with parents and F1 progeny, to determine heterotic patterns, correlations, heritability and combining ability of various kernel physical features. The relative importance of additive vs. non-additive genetic effects was also determined. The general combining ability (GCA) and specific combining ability (SCA) components of variance were significant for all of the features examined, but reciprocal effects (RE) were significant only for kernel projected area (KPA) and kernel rupture strength (KRS). GCA effects were dominant for kernel length (KL), KPA, kernel sphericity (KS) and thousand kernel weight (TKW). The magnitude of GCA variance was more pronounced than SCA variance for all these features. However, SCA effects were dominant for kernel width (KW), kernel height (KH) and KRS. KRS, an important parameter during sowing, harvest and milling, had significantly positive linear correlations with KL, KH, KPA and TKW and negative correlations with KS. TKW in durum wheat can be increased by selecting progenies with high KL, KH and KPA values whereas the opposite is true with higher KW and KS values. Accordingly, the parent Iri used in this study appears to be a suitable donor in breeding programs where improved kernel physical features are desired. Path and stepwise regression analyses revealed that KH has been the major feature in increasing TKW due to its high direct effect on this feature. On the other hand, KW and KS were the main features directly contributing to higher KRS values. It is suggested that early selection of breeding lines with respect to higher KH and to higher KW and KS should help breeders to improve cultivars with better KRS and TKW values, respectively. © 2003 Elsevier B.V. All rights reserved.