This study was carried out to determine the effect of probiotic on growth performance and hematological indices in male rainbow trout (Oncorhynchus mykiss) broodstock. For this purpose, broodstock with an average initial weight of 1366.14 ± 33.85 g (mean ± S.E.M) were fed for 8 weeks with diets containing 0, 0.5, 1 and 2 g.kg^-1 Bio-Aqua probiotic. At the end of the period, growth performance and blood parameters were evaluated. According to the results, the highest average final weight and the lowest feed conversion ratio was observed in 1 g.kg^-1 treatment and showed a significant difference with control treatment (P<0.05). Moreover, the highest specific growth rate and body weight increase were obtained in 1 g.kg^-1 treatment and showed significant difference with control and 2 g.kg^-1 treatments (P<0.05). The condition factor was not significantly different among treatments (P>0.05). In hematological indices, the highest number of red blood cells and hemoglobin levels were observed in 1 g.kg^-1 treatment and showed significant difference with control and 2 g.kg^-1 treatments (P<0.05). The highest number of white blood cells and hematocrit percentage were obtained in 1 g.kg^-1 treatment and showed significant difference with control treatment (P<0.05). However, significant difference were not observed in other hematological indices among the treatments (P>0.05). The results of present study demonstrated the ability of probiotic to influence on growth parameters and hematological indices in male rainbow trout broodstock. Accordingly, the Bio-Aqua probiotic in 1 g.kg^-1 as the best level suggested to using in feed of male rainbow trout broodstock.