The aim of this study was to investigate the effect of Spirulina platensis extract on the number of spermatogenic cells of rats with excessive physical exercise. Excessive physical exercise was achieved through one hour of swimming for 35 days. Twenty male rats were divided into five groups i.e (1) C-, control group, (2) C+, a group was only given swimming, (3) T1, a group was given 300 mg/kg BW of Spirulina platensis and swimming, (4) T2, a group was given 600 mg/kg BW of Spirulina platensis and swimming, and (5) T3, a group was given 1200 mg/kg BW of Spirulina platensis and swimming. Spirulina platensis extract was given orally once a day before swimming.ANOVA test followed with Duncan test showed that the number of spermatogenic cells significantly different among treatments (p<0.05). Excessive physical exercise was able to influence on the male reproduction system by declined on the number of spermatogenic cells in seminiferous tubules of male rat. The conclusion of this study was dose of 1200 mg/kg BW of Spirulina platensis extract could maintain the number of spermatogenic cells of male rat after excessive physical exercise.