To establish whether or not androgens is responsible for the induction of vitellogenin(Vg) synthesis and secretion, primary hepatocytes prepared from immature eels were used. The results are follows: 1. Eel hepatocytes were prepared using a collagenase perfusion technique. The isolated cells attached efficiently to fibronectin-coated dishes and subsequently formed monolayers in serum-free medium. These cultures maintained in medium for 10 days with minimal cell loss. 2. Estradiol-17$eta$(E2) alone was insufficient to induce Vg synthesis. The combination of E2 with methyltestosterone(MT) markedly stimulated Vg synthesis. High vg production occurred in MT concentration from 10-6~10-5M in the presence of E2 (10-6M). Testosterone and androsterone were also effective, but progesterone was not effective in inducing Vg synthesis. Neither MT alone nor testosterone and androsterone alone had any effect on Vg synthesis. 3. E2-primed hepatocytes showed Vg synthesis in both media with and without hormones 1 day after culture. In the cultures with the vehicle, MT, or progesterone, the rate of synthesis seemed to decrease with time. But the combination of E2 and MT showed an intense increase in Vg synthesis. Hepatocytes isolated from E2-primed eels also required androgens for continuating of Vg synthesis. 4. These results demonstrate that androgens act together with E2 in synthesis and secretion of eel Vg.