This study focuses on the endocrine-disrupting capabilities of paper and pulpmill effluents discharged into Elevenmile Creek, FL; specifically effects of effluents on levels of testosterone, 11-ketotestosterone, estradiol in blood, vitellogenin production, gonadosomatic index, and condition coefficients in bluegill sunfish, Lepomis macrochirus. Bluegill were captured monthly for one year from Elevenmile Creek and a reference site---Blackwater River. Standard length and weight were recorded, and blood samples were collected. All hormone and vitellogenin levels were measured by ELISA. The reproductive cycle of bluegill in the southeastern United States in a blackwater system was also determined from reference site data. The livers of formalin fixed specimens archived in Tulane's Museum of Natural History from Elevenmile Creek and from the reference site were immunohistochemically examined in an attempt to detect historical differences in vitellogenin production between fish from the two sites. The alternate hypothesis of this investigation was that female bluegill would exhibit a type of masculinization as seen in female mosquitofish captured from this site, indicating an androgenic effect of this type of contamination. Results of Chapter II show that, when compared to reference females, females from Elevenmile Creek exhibited significantly higher levels of estradiol in Spring 2001 (5.50 ng/ml vs. 2.30 ng/ml), vitellogenin in Winter 2001 (2833.70 mug/ml vs. 187.96 mug/ml). When compared to reference males, males from Elevenmile Creek exhibit higher levels of estradiol in Summer 2001 (5.96 ng/ml vs. 2.27 ng/ml), and vitellogenin in Fall 2600 (1136.20 mug/ml vs. 86.57 mug/ml). There was no evidence of masculinization of females or supermasculinization of males. The added nutrients, food supply, and species differences are all plausible explanations for the increased levels of hormones and vitellogenin in bluegill from Elevenmile Creek The reproductive cycle of bluegill found in Florida in blackwater system, displayed in Chapter II begins in spring (April) and continues through the summer (September). In Chapter III, vitellogenin was detected in formalin fixed livers. Historical evidence also shows that exposure of paper and pulpmill effluents has had no adverse effects on the reproductive physiology of bluegill sunfish in the past