Serum and follicular fluid concentrations of estradiol-17 beta (E2), progesterone (P), testosterone (T), 4-androstene-3,17-dione (A-4), dehydroepiandrosterone (DHA), DHA sulfate (DHAS), sex hormone-binding globulin (SHBG) and serum cortisol were studied in 50 non-smoking and 50 smoking women in an IVF program. Follicular fluid concentrations were also compared in follicles which gave rise to cleaved oocytes (TYPE I) and follicles which failed to yield fertilized oocytes (TYPE II) in the same woman.