The purpose of this controlled clinical trial was to demonstrate possible correlations between changes in bioenergetic metabolism and psychotropic drug administration in the treatment of functional psychosis. The study included twenty-six patients, eleven with schizophrenia, three with chronic atypical depression and twelve with drug-resistant endogenous depressions. All patients were kept on continuous psychotropic medication for at least 3 weeks before starting the trial, and piracetam was given additionally in a fixed dosage of 2400 mg daily; the same number of identical capsules was given during the pre- and post-treatment placebo periods. Psycho-pathological evaluation of the patients was by the BPRS; clinical and biochemical data were evaluated statistically by the analysis of regression. The results show that in schizophrenic patients an improvement was observed in those cases who had improved biochemically, i.e. where the ATP values had increased. In drug-resistant depressions there was a rapid and significant clinical improvement after piracetam co-administration, and this went in step with a significant rise in ATP levels.