Equisetum arvense L. (common horsetail) has medicinal characteristics that have been known since ancient times and are used to cure a variety of ailments. The effect of E. arvense L. on rats with induced osteoporosis was investigated. Forty female rats were randomized in 5 equal groups (n=8). The first group was working as tricks (SHAM) (negative control), while the other 4 groups were operating with ovariectomized (OVX) and fed on basal diet deficient in calcium and were given orally prednisone acetate (4.5 ml/kg body weight/day twice a week) for two weeks as source of glucocorticoid, to induce osteoporotic models. Three weeks after ovarian removal, Group 2 kept as positive control (OVX) and the other three groups were fed on basal diet supplemented with 5, 10 and 15% of dried E. arvense L, respectively for 8 weeks. The results showed that rats fed on dried E. arvense at all tested levels had significant increase (P