The extract of root bark of Salacia oblonga (SO) belonging to the family Celastraceae was tested for the anti-mutagenic activity using sperm abnormality test in Wistar rats. The hydroalcoholic extract (0.5 and 1 gm/kg, b.w, p.o. daily for 7 days) was evaluated against Mitomycin-C (MMC-2 mg/kg, b.w, i.p.) induced testicular toxicity by estimating the sperm shape abnormality and sperm count. The sampling was done after 48 hours and 72 hours of the clastogen treatment. The antioxidant activity of the SO was evaluated by measuring the serum levels of superoxide dismutase(SOD) and catalase. The results indicated that prior treatment of SO had suppressed the changes produced by MMC. SO at a dose of 1.0 gm/kg bw had shown significant (p<0.01) inhibition in the sperm shape abnormality and sperm count in both the time intervals, while the lower dose (0.5 gm/kg, b.w) showed inhibitory effect mainly at 48 hr duration compared to the MMC group. The results also indicated that SO has improved (p<0.01) the status of serum antioxidant enzymes compared with the MMC group. The data from the study suggests that SO possess antimutagenic effect against MMC and the activity could be due its antioxidant potential.