Senecio biafrae is a medicinal plant widely used by traditional healers in the western region of Cameroon for the treatment of woman infertility. In the course of the evaluation of its effect on puberty onset and some physiological parameters of fertility, different doses of its ethanolic extract were orally administered to immature female rats for 30 days. Body, ovarian, uterus weight; uterine, ovarian proteins or cholesterol level as well as data on puberty onset were recorded. A linear increase in the growth rate of all animal was observed throughout the experimental period. From the 27 th day till the end of treatment, the body weight gain of rats treated with 8 mg/kg was significantly increased (p<0.05) compared to that of control animals. The age of animals at vaginal opening (VO) was significantly reduced (p<0.05) in those treated with the dose of 8 mg/kg (41.54 ± 0.50) compared to control animals (43.33 ± 0.73). Ovarian weight and uterine protein level of animals treated at 64 mg/kg significantly increased (p<0.05). A reduction in the number of corpora lutea with doses of 32 and 64 mg/kg as well as an increase in the resorption index with doses 8 and 64 mg/kg were also noticed. Overall, the present results provide evidence on the estrogenic effect of the ethanolic extract of Senecio biafrae leading to the acceleration of puberty onset in immature female rat.