Genes, leading to the death or sterility of distant hybrids, are well known in cultivated plants. The paper summarizes own data on the genetics of hybrid lethality, which was discovered in the crosses of bread wheat and inbred lines of rye. It shows that hybrid lethality is a consequence of a negative interaction between the complementary genes of wheat and rye. However, embryonic lethality, which is typical for some wheatrye hybrids, cannot be attributed to the evolutionary originated interspecific incompatibility, which is a wellstudied prezygotic incompatibility of common wheat and its related genera.