Ethnopharmacological relevance: Radix Astragali (RA), Radix Angelicae Sinensis (RAS) and Folium Epimedii (FE) are three of the extensively applied herbs among traditional Chinese medicines for gynecological disorders and osteoporosis. A derivative herbal formula-RRF, consisting of the three medicines with a weight ratio of 5:1:5, is derived from a famous Chinese herbal formula-Danggui Buxue Tang (DBT). RRF has shown noteworthy perimenopause ameliorating effect in both ovariectomized rats and natural aging female rats, which might represent a promising candidate for the treatment of perimenopausal disorders. The aim of this study was to evaluate its immunological potential, chronic toxicity and reproductive effects by 26-week repeated daily administration in female rats, in order to optimize its safe use. Materials and methods: The effect of RRF on immunological function was studied by macrophage phagocytosis, immune organ index, serum immunoglobulin level as well as delayed type hypersensitivity (DTH) in mice. For toxicity assessment, acute toxicity study was performed according to fixed dose procedure with a single oral administration of RRF to mice. In the oral chronic toxicity, 120 female rats were administrated RRF orally in 0, 1100, 4400, or 8800 mg/kg/day doses for 26 weeks. Clinical signs, mortality, body weights, feed consumption, haemato-biochemical parameters, organ weights, histopathology and reproductive hormone profiles were examined at the end of the 13- and 26-week dosing period, as well as after the 4-week recovery period. Results: Oral administration of RRF at three doses (282, 564 and 1128 mg/kg) significantly increased the indices of phagocytosis K, as compared with prednisone acetate (PR) group (p < 0.05 or 0.01). Exposure of RRF dose-dependently boosted circulating serum IgM level (all p < 0.01) in response to CRBC in PR induced mice. Furthermore, RRF treatment elicited a significant increment (all p < 0.01) in DNFB-induced DTH response and the immune organ indices in a dose-dependent manner in mice, in parellel to DNFB-induced group. In the single dose acute toxicity and repeated dose 90-day chronic toxicity investigations, no toxic signs/mortality were observed. RRF treatment did not cause any toxicologically significant changes in clinical signs, food consumption, body weight, relative organ weight, hematological parameters, clinical chemistry, gross pathology and histopathology between treatment and control groups. No treatment related gross/histopathological lesions were observed and no target organ was identified. Long-term repeated administration of RRF exerted a significant promotion on serum level of steroid hormone estradiol, progesterone and testosterone release, along with decrease of circulating pituitary follicle stimulating hormone, luteinizing hormone, and prolactin levels in female rats. The No Observed Adverse Effect Level (NOAEL) of RRF was determined to be over 8800 mg/kg/day for elderly female rats, a dose that was equivalent to 50 times of human dose. Conclusion: The present investigation demonstrated that RRF possessed appreciable immunopotentiating activity and had a relatively wide margin of safety. Long-term treatment of RRF exhibited estrogenic properties, and retarded certain age-associated degenerations. RRF might have the potential for further development as a safe and effective alternative/complementary to conventional medication in relieving perimenopausal symptoms. (C) 2016 Published by Elsevier Ireland Ltd.