Combining ability and stability performance for seed yield/plant and its component traits viz., capsules/plant, seeds/capsule and 1000-seed weight were studied in the F3 and F4 generations of 36 diallel crosses involving nine flax parents over three diverse environments. GCA/SCA mean squares indicated that both additive and non- ad­ditive gene effects governed the inheritance of seed yield/plant and its three component traits. However, additive was more important than non-additive genetic variance in the genetic expression of 1000-seed weight, seed yield/plant and capsules number/plant. On the other hand, non- additive was more important than additive genetic variance in the inheritance of seeds/capsule, Significant GCA x E interaction indicated that the additive effects were not stable over environments, hence more than one test environment is required to obtain reliable informa­tion for seed yield/plant and its components_ On the contrary. SCA x E interaction was not significant for seed yield /plant and seeds/capsule indicating that the non-additive effects governing these two characters were less distorted by environmental fluctuations. Giza-8 and 9.2419/1 were good combiners for seed yield/plant, capsules/plant and 1000-seed weight, whereas Ariane-R3 was good combiner for seeds/capsule_ Nine out of the 36 studied crosses showed positive and significant SCA effects for seed yield/plant or its three components over environments in both F3 and F4 generations. Two out of these nine superior crosses, Giza 8 x Ariane-R3 and 82419/1 x Ariane-R3 involved high x high gener­al combining parents for seed yield /plant and one or more of its compo­nents. Moreover, the cross 9.2419/1x 5.148/6/1 showed positive and significant SCA effects for seed yield /plant plus two of its components 1000-seed weight and seeds /capsule. Stability analysis showed that the five crosses, (Giza 7 x Giza 8, Giza 7 x S.2419/1, Giza 8 x 9.2419/ 1, Giza 8 x S.148/6/1 and 9.2419/1 x S.148/6/1) were consistent for seed yield /plant and its two important components, 1000-seed weight and capsules/plant in F3 and F4 generations. Hence these five crosses were considered adapted and may be useful as potential breeding mate­rial for developing crosses with stable seed yield /plant in later genera­tions. It concluded that early generation for yield and stability perfor­mance would provide reliable information for improving seed yield in flax.