Taurine applied to rats intracerebroventricularly in doses 0.1--3.0 mg increased ACh level and decreased ACh synthesis in the cerebral cortex. In the striatum ACh level was increased after doses of 0.1--3.0 mg and ACh synthesis was decreased after 0.01--3.0 mg. In the hippocampus taurine appeared to decrease both ACh level (0.5--3.0 mg) and synthesis (0.1--3.0 mg). Maximum effects of taurine were observed 30--60 min following the injection. A possible role of taurine as a neurotransmitter or neuromodulator is discussed.