Smilax myosotiflora, a popular local aphrodisiac is known to increase sexual libido. How-ever, the aphrodisiac efficacy of S. myosotiflora has not yet been scientifically established. Present investigation describes the effects of S. myosotiflora on testicular 11β-hydroxysteroid dehydrogenase (11β-HSD) oxidative activity and the levels of plasma corticosterone and tes-tosterone. Male Wistar rats (200-250g) were given either 8 mg/kg BW/day of S. myosotiflora or 120 μg/kg BW/day of Mifepristone (RU486, a glucocorticoid receptor (GR) antagonist) or both together (RU486+S. myosotiflora), for seven consecutive days. Results between groups were analyzed using analysis of variance (ANOVA) and Student’s t test. Differences were considered significant at P<0.05. Rats given S. myosotiflora showed no significant changes in 11β-HSD activity but had increased corticosterone (P<0.01) and decreased testosterone (P<0.01) levels compared to controls. Administration of RU486 alone decreased 11β-HSD activity (P<0.001), but increased testosterone levels (P<0.05) compared to controls. Con-versely, rats with RU486+S. myosotiflora showed increased 11β-HSD activity (P<0.001) but decreased testosterone levels (P<0.05) compared to RU486-treated rats. In the rats treated with RU486+S. myosotiflora, none of the parameters differed significantly from controls. Plasma corticosterone levels were found to be lowered in rats treated with RU486+S. my-osotiflora compared to S. myosotiflora-treated rats (P<0.05) towards control values. In this study, S. myosotiflora at a dose of 8 mg/kg BW/day was found to increase corticosterone with a corresponding decrease in testosterone levels. Previous studies show that RU486 acts through GR in affecting 11β-HSD activity and hormone levels. Since RU486+S. myosotiflora rats show opposite effects from RU486 rats, we therefore suggest that the actions of S. my-osotiflora on these parameters are possibly mediated through the GR. S. myosotiflora and RU486 probably competitively inhibit each other at the GR level.