Consumption of choline by rats sequentially increases serum-choline, brain-choline, and brain-acetylcholine concentrations. In man consumption of choline increases in levels in the serum and cerebrospinal fluid; its administration is an effective way of treating tardive dyskinesia. We found that oral lecithin is considerably more effective in raising human serum-choline levels than an equivalent quantity of choline chloride. 30 minutes after ingestion of choline chloride (2-3 g free base), serum-choline levels rose by 86% and returned to normal values within 4 hours; 1 hour after lecithin ingestion, these levels rose by 265% and remained significantly raised for 12 hours. Lecithin may therefore be the method of choice for accelerating acetylcholine synthesis by increasing the availability of choline, its precursor in the blood.