We crossed the 14 D-genorne disomic substitutions of durum wheat cv. Langdon with an inbred rye and obtained a large variation in crossability percentages in the 1995-1996 and 1996-1997 growing seasons. The results showed that chromosomes 2A, 2B, 3B and 5B of Langdon carry crossability genes, while chromosomes 4B, 5A, 6A and 7A are involved in a suppressing effect on crossability with rye. Of which, chromosomes 2B and 3B showed a stronger effect on crossability than chromosome 5B, and chromosomes 4B and 7A showed a stronger effect than chromosome 5A. Thus, it was indicated that the tetraploid wheat cv. Langdon has a different kr system regulating crossability with rye in comparison with that of hexaploid common wheat.