In the three-year period, 1989-1991, the yield capacity of durum wheat was compared with that of bread wheat and barley, in order to evaluate the adaptability of the latter crops to a semi-arid environment. Four cultivars, chosen among the most grown and productive, were examined for each species. The meteorological patterns of the 3 cropping seasons were extremely diverse with particular regard to rainfall distribution, and seemed representative of the variability of the trial environment. Highly significant ''species x season' and ''cultivar x season'' interaction was observed for grain yield and for most of the other recorded traits. In the first cropping season, which was characterized by a moderate stress, barley was the most productive species. In the second, characterized by more severe drought, bread wheat and barley achieved yields which were double that of durum wheat. In the third season, which was meteorologically favourable, no significant productive differences were found between the species. Overall, bread wheat and barley proved more reliable than durum wheat for yield in the region.