We investigated the effect of alpha/beta interferon on neuronal survivability. E16 murine telencephalic vesicles were dissected aseptically and grown on collagen-coated coverslips. After 2 weeks of culturing, the media was supplemented with mouse alpha/beta interferon (1,500 U/ml). After an additional 2 weeks of culturing, all of the control cultures demonstrated significant neuronal death. In the 16 interferon-treated cultures, neuronal death took place only in 1 culture, baseline survivability occurred in 2 and proliferation in 13 cultures (p < 0.005). Thus, alpha/beta interferon sustains neuronal growth.