Introduction: Stachys lavandulifolia is a Plant of the lamiaceas family and have flavonoid compositions. The aim of this study is to investigate the effects of hydroalcoholic extract of stachys lavandulifolia on the hormonal Pituitary-Gonadl axis and testis tissue changes in adult male rat.

Materials & methods: In this experimental study fifty adult male rats of wistar race were divided into 5 groups of ten: The control group received normal diet, shame group took distilled water and experimental groups were intra peritoneal (i.p.) injected by 50, 100, 200 mg per kg body weight extract of stachys lavandulifolia. At the end of the 30^th day, blood samples and levels of FSH, LH, testosterone and dihydrotestosterone were measured. Also, from tissue sections of testis tissues were taken. The collected data were analyzed by the SPSS software using ANOVA and t-test.

Findings: A significant increased concentration of LH and FSH hormones was observed in experimental groups receiving the maximum extract in compared with the control and shame groups (P<0.05). Concentration of testosterone hormone in maximum dose of extract and DHT hormone in intermediate and maximum doses of extract showed a significant decrease compared to the control and shame groups (P<0.05). Also, a histological study of the number of spermatocyte cells in seminiferous tubules of the testis of the maximum dose showed   a significant reduction compared to the control and shame groups (P<0.05).

Discussion & conclusions: According to the results, stachys lavandulifolia extract reduces the amount of testosterone and DHT hormones. Apigenin in extracts will possibly impair the function of the male reproductive system.