Chromosome association and fertility of the hybrids of C. persicum (2n=2x=48)xC. hederifolium (2n=34) and the amphidiploids were compared with their parental species. The mean chromosome association per PMC at metaphase I in meiosis was 0.13 I + 23.93 Iin C. persicum and 0.15 I +16.92 II in C. hederifolium. These parental species formed normal cells at telophase I and the tetrad stage, and produced viable pollen grains and seeds. On the other hand, the hybrids (2n=41) showed partial chromosome association with a mean of 35.39 I + 2.81 II . They formed abnormal cells at telophase I and the tetrad stage, which resulted in sterile pollen. The hybrids failed to set a seed by cross-pollination with fertile C. persicum pollen grains, suggesting female sterility. In the amphidiploids (2n=82), bivalents were formed at high frequency and the mean chromosome association was 0.51 1 +40.75II. Meiosis proceeded normally and fertile pollen grains were produced. These amphidiploids yielded viable seeds by self- pollination. These observations suggest that C. persicum and C. hederifolium are distantly related within the genus Cycl amen.