Accumulation of benzo[α]pyrene (BaP) by sexually mature flatfish gonad, its transfer to developing gametes, and its subsequent effects on developing embryos were studied. Thin‐layer chromatography revealed both unmetabolized BaP and polar metabolites in the ovary, wolffian ducts, oocytes, and semen of English sole 24 h after ip injection with 200 μCi [3H]BaP. Concentrations of BaP and its metabolites were 3–11 times higher in oocytes and semen than in gonadal tissue. Fertilized eggs from flathead sole that had been fed 4.0 mg BaP 5 h before spawning demonstrated a significantly lower (p < 0.001) hatching success (11.9%) than eggs from control fish (56.6%). Morphological abnormalities were found in only 1.6% of control embryos but in 5.6% of embryos from treated females.