OBJECTIVES: Excessive fluoride ingestion causes a disease known as fluorosis which prevailing in more than 50 countries and regions. A large number of studies have shown that excess fluoride can cause human reproductive system damage. Therefore, we investigated the possible association between estrogen (E) level with fluorosis and the role of selenium in fluorosis women in Shaanxi province. METHODS: Ziyang County of Ankang City has higher environmental selenium level, while the Hanbin district of Ankang City has lower environmental selenium level. Ziyang County and Hanbin district of Ankang City were both the serious fluorosis areas. The fluorosis women patients from different environmental selenium level area and the healthy volunteer were divided into three groups: “High Se + F group” (n=50), “High F group” (n=50) and “Control group” (n=46). All women were among 20 to 49 years old. Elevel was examined by ELISA kit. The selenium level in hair was tested with Atomic Fluorescence Spectrophotometer. RESULTS:  The E was significantly lower in “High F group” than that in “High Se + F group” and “Control group” (27.11±1.91, 60.22±6.95, 63.57±2.24 pg/ml, respectively). The mean for total Se concentration in hair was different: 3.67±0.16 μg/g in “High Se + F group”, 0.99±0.09 μg/g in “High F group” and 0.66±0.13 μg/g in “Control group”, respectively. CONCLUSIONS:  The Elevel in fluorosis women was lower than that in control group women, while the Se has the protective effect against fluoride by increasing the E level. Women lived in fluorosis areas should intake more Se to prevent ovarian function damage induced by fluoride. This research was supported by National Natural Science Foundation (No. 81172610), Huimin projects of Ministry of Science and Technology (No. 2012GS610101), Science and technology projects of Shaanxi province health department (No. 2014ZD072) and projects of Shaanxi Province Administration of traditional Chinese Medicine (13-LC085).