Teucrium polium L. (Lamiaceae) is a commonly used medicinal plant in folk medicine. Among several uses, T. polium is used to treat male fertility problems. This research was conducted to study the effect of T. polium on spermatogenesis, testosterone level, androgen receptor expression, and fertility in male rats. Administration of hexane extract for 6 days to aging rats increased testosterone level. When administered for 60 days, T. polium hexane extract downregulated androgen receptors, decreased sperm count without producing histological changes in different stages of spermatogenesis. Also, fertility index decreased without making teratogenic effects when treated males were mated with untreated females on the 55th day of extract administration. Therefore, the downregulation of androgen receptor could be due to the continued elevation in testosterone level over time. In conclusion, this study suggests that the prolonged use of T. polium in folk medicine may negatively affect male fertility.