Summary:In this study, the effects of half, normal and double clinical doses of artesunate; artesunate/sulfadoxine/ pyrimethamine; artesunate/amodiaquine and their combinants (sulfadoxine/pyrimethamine and amodiaquine) on the basal serum levels of testosterone, FSH, LH and prolactin of the guinea-pig were investigated. The results of this study showed that the agents caused significant decreases (p<0.05) in serum testosterone level, with varying effects on LH, FSH and prolactin. Testosterone level was decreased by artesunate (37%), sulfadoxine/pyrimethamine (22%), amodiaquine (14%), artesunate/sulfadoxine/pyrimethamine (41%) and artesunate/amodiaquine (49%) at the clinical dose, compared to the serum levels in control animals. Furthermore, artesunate and amodiaquine also caused moderate decreases in the serum concentrations of LH and FSH, without an effect on prolactin. The effects of these agents may be due to oxidative stress on the reproductive system of the organism.