The present study investigated the sperm quality parameters and platelet indices in adolescent and adult varicocele rats. Twenty male Wistar rats were distributed into four groups (n = 5): I—sham adolescent group, II—sham adult group, III—varicocele adolescent group, and IV—varicocele adult group. Rats were sacrificed on the 61st day of the experiment. Sperm count (×106 ml−1), sperm motility and viability (%) were significantly (p < 0.05) different between varicocele and sham groups in adolescent and adult rats. Varicocele adults had significant (p < 0.05) lower platelet count (PLT) than sham adolescents and adults. The mean platelet volume (MPV), the MPV/PLT ratio, plateletcrit (PCT) and platelet distribution width (PDW) differ significantly (p < 0.05) between varicocele and sham groups of adolescent and adult rats. It is the first time the ratio MPV/PLT was evaluated in association with other platelet indices in adolescent and adult varicocele rats. Based on the results, it would appear these indicators can become a promising tool in varicocele diagnosis.