Induction of hybrid and allotriploid between female rainbow trout, oncorhynchus mykiss and male cherry salmon, O. masou were performed. Triploid rate in allotriploid was 92% and the survival rates of allotriploid exceeded that of their hybrid counterparts. Karyological studies revealed that the hybrid had exactly the same intermediate diploid karyotypers as that of two parental species, while allotriploid had two sets of the maternal haploid complement and one set of the paternal haploid complement. Hybrid revealed an intermediate size in celluar and nuclear size of erythrocyte, while allotriploid revealed larger cellular and nuclear size of erythrocytes than hybrid. The number of nucleolar organizer regions of hybrid were 1 or 2, while those of allotriploids were 1, 2 or 3. These results proved that allotriploidization can lead to increase cytogenetical characters compared to counterpart hybridization.