1. The effect of norepinephrine (NE) on progesterone production in hen granulosa cells was examined. After 4 days of the culture, the progesterone production was stimulated by chicken LH but not by NE during a 4 hr incubation. 2. The LH-stimulation progesterone production was not affected by the presence of NE when given together with LH, but was significantly increased when the cells were precultured with NE for 2 days. 3. The effect of NE was inhibited by phentolamine, but not by propranolol. 4. The results indicate that NE may enhance the responsiveness of the hen granulosa cell to LH through alpha-adrenergic receptors.