The authors screened the pharmacological effects of 50% ethanol extracts of Yacon on spermatogenesis in rats. Numbers of sperm in animals treated with 25, 50, or 100 mg/kg/day for 6 weeks of Yacon tuber extracts (YTE) were approximately 1.51, 1.61 and 1.78 times higher, respectively, than in the untreated control group. Moreover, the spermatogenic effect of Yacon leaf extract was found to be $1.03{sim}1.38$ times higher than that of YTE. The ameliorative effect of Yacon tuber extracts on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced toxicities in the rat were also investigated. Rats were assigned to three groups (6 rats/group), a control group, a TCDD exposed group, and a group treated with Yacon tuber extract (YTE) after TCDD exposure (TCDD/YTE group). 40 ${mu}g/kg$ of TCDD was injected i.p., and 200 mg/kg/day of YTE was also administered for 4 weeks by oral gavage. The TCDD/YTE group showed a significant increase in sperm number as compared with the TCDD exposed group. In conclusion, TCDD induced testicular toxicity was significantly ameliorated by YTE. The results of the present study suggest that Yacon extract is a possible therapeutic for the treatment of spermatogenic disorder.