The effect of piracetam, a cyclical derivative of GABA, was compared with that of a placebo in a double-blind study of 60 patients with post-concussional syndrome of 2-12 months' duration. The daily dose of piracetam was 4,800 mg. After 8 weeks of treatment piracetam significantly reduced the occurrence and severity of the following symptoms: vertigo, headache, tiredness, decresed alertness, increased sweating and neurasthenic symptoms. No significant effect was observed on the following symptoms: tremor, orthostatic symptoms, and memory disorders. Side effect were reported by 64% of the patients under piracetam and by 32% under placebo. In the author's opinion, piracetam seems to be a promising new drug for the treatment of post-concussional syndrome.