The effects of several mammalian reproductive toxins on reproductive endocrine function in female Atlantic croaker (Micropogonias undulatus) were examined. Croaker were exposed to sublethal concentrations of lead, cadmium, benzo[a]pyrene (BaP), or a polychlorinated biphenyl mixture (Aroclor 1254) for 1 month during the period of ovarian recrudescence. Reproduction was altered after exposure to all four chemicals. The plasma levels and secretion rates of reproductive hormones were augmented after exposure to cadmium resulting in precocious ovarian growth. In contrast, treatment with lead, BaP, or Aroclor 1254 caused a decline in circulating steroid hormone levels and ovarian growth. Changes in hormone secretion rates from isolated pituitary and ovarian tissues incubated in vitro were also observed after exposure to several of the reproductive toxins. It is concluded that the Atlantic croaker is a sensitive model for examining the effects of reproductive toxins on female reproductive endocrine function. Our results indicate that these chemicals may act at various sites on the hypothalamus-pituitary-gonadal axis to alter reproductive endocrine function.