Abstract: The present study was carried out during 2008/2009 and 2009/2010 to obtain information about the performance of wheat genotypes, gene action and asses the combining ability of parental genotypes and their F1' s under Libyan conditions by using diallel fashion. The analysis of variance revealed that mean squares due to genotypes were highly significant for all studied characters indicating wide diversity among the parental materials used in the present study. Giza 165 variety had the highest number of spikes/plant, spikes weight/plant and grain yield/plant compared with the other parents. Crosses (Sakha 69xSakha 8) and (Sakha 69xGiza 165) gave the highest grain yield/plant compared with the other F1 crosses. Mean squares due to both general (GCA) and specific (SCA) combining abilities were highly significant for all studied traits, except SCA for plant height and GCA for No. of spikelets/spike. These results indicated that presence both of additive and non-additive types of gene action in the genetic system controlling the studied traits. The ratio of Σgi2/Σsij2 variance was less than unity for all studied traits, suggesting that non-additive gene effects were more important than the additive ones in the expression of these traits. The regression analysis for days to heading, number of tillers and number of spikes/plant revealed that positive intercepts of Wr/Vr regression line supported an additive gene action with partial dominance and the selection in early generation may be fruitful for these traits. On the other hand, the regression analysis for plant height, spikes weight and grain yield/plant revealed that negative intercepts of Wr/Vr regression line supported an over dominance gene action and the selection in early generation may be unfruitful for these traits.