AbstractWe have developed anin vitrobioassay for nerve growth factor (NGF) which offers several advantages over currently used alternatives. The assay uses the commercially available PC-12 cell line, and requires only 24 hr incubation with NGF. The cells do not require priming, and are dosed as they are originally seeded in serum-free medium in 96-well cell culture plates coated with collagen. Concentrations between one and 20 ng/ml NGF can be measured, and only standard cell culture equipment and a microplate reader are required.