Low levels of natural and synthetic estrogens have been detected in soil, water, and sewage treatments for the past many years and their ability to interfere with reproductive functions of living organisms has become a growing concern. Exposure to natural estrogens such as 17ß-estradiol and estrone in soil and water can cause sterility in fish, gastropods, and birlds (Peterson et al., 2000). Remediations rely on a mechanistic understanding of environmental processes that influence estrogen fate. Previous studies have demonstrated that phenolic compounds can be abiotically degraded by redox-active soil and sediment components such as metal oxides. Our objectives were to determine the abiotic degradation of 17ß-estradiol in soil, to identify the oxides responsible, and to evaluate the factors influencing the degradation. Batch experiments were conducted to determine the kinetics of 17ß-estradiol degradation in soil. 17ß-estradiol solutions were mixed with 0.15 g of autoclaved original soil or Mn-oxides free soil. Results showed that 17ß-estradiol was rapidly oxidized to estrone in original soil. No degradation was observed in Mn-free soil, suggesting that the soil manganese oxides were responsible for the degradation. The concentration of Mn(II) in soil increased in the presence of 17ß-estradiol, further confirming the oxidative role of manganese oxides. The degradation was faster at pH 7.7 than at 4.4, consistent with the oxidative mechanism. Mn-free soil was used to determine the sorption of 17ß-estradiol and estrone to eliminate the potential influence of degradation on sorption.The total recovered 17ß-estradiol and estrone in soil gradually decreased to constant values of 84 and 72%, suggesting that fractions of 17ß-estradiol and estrone became irreversibly sorbed. These results indicate that 17ß-estradiol is abiotically oxidized to estrone by soil manganese oxides. 17b-estradiol and estrone become partially unavailable in soil due to irreversible sorption, and thus may increase their persistence.