Operation Sweep (OPS) de rheumatism powder is a registered Nigerian poly-herbal medicine. The acute and sub-chronic testicular toxicology of the OPS powder was investigated in male albino rats. The rats, divided into 10 per group, received aqueous extract of the OPS powder, orally, at 0, 0.75, 1.50, 2.25 g/kg for 30 days. Animals were sacrificed on day 30; the testes and epididymis were excised and weighed. The testes were processed for histological analysis, and the epididymis was used for sperm quality: epididymal sperm count (ESC), epididymal sperm motility (ESMot) and the epididymal sperm morphology (ESMor) determination. The results showed a non-significant increase in the body weights of the treated groups. Treatment with OPS caused a significant (p < .05) reduction of the relative weight of the epididymis in the 2.25g/kg dose group; a significant (p < .05) decrease in the ESC and active ESMot, an increase in the dead ESMot, and a nonsignificant (p > .05) effect on the ESMor. Histologic examination of the testes indicated no serous pathological changes except for some mild vascular congestion at 1.5 and 2.25 g/kg. This study suggests that the aqueous extract of the OPS powder may cause epididymal toxicity as shown in the adverse effect on sperm quality.