The effectiveness of oxiracetam (1600 mg/day) vs placebo was assessed in a group of 96 out-patients suffering from cognitive disorders secondary to primary degenerative dementia. The study, performed in double-blind, lasted 26 weeks and is expected to be continued in open conditions until a whole year of treatment is completed. The assessment of the results obtained at 6 months was carried out following both the methodology based on neuropsychological tests and scales, and the study of the simple reaction time by any of a computerised portable tachystoscope. The patients treated with oxiracetam showed a statistically significant improvement of cognitive function and simple reaction time. No significant variations in the scores of the tests used were observed in the placebo group. The patients themselves appeared in favour of oxiracetam. The drug tolerability proved to be very good for the whole duration of the treatment. The authors believe that oxiracetam favourably acts on the symptoms of senile cerebral deterioration and can improve the capability of information processing, as suggested by the better performances obtained at the reaction time tests.