The effectiveness of Oxiracetam (1600 mg/day) versus placebo was assessed in a group of 96 out-patients suffering from cognitive disorders secondary to primary degenerative dementia. The study lasted twelve months and was performed in two stage, a) double-blind (26 weeks) and b) open study (26 weeks). The assessment of the results obtained at two, six and twelve 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 computerized portable tachystoscope. The patients treated with Oxiracetam showed a statistically significant improvement of simple reaction time and cognitive function detected by the Attention matrix. In the placebo group after twelve months a significant worsening of cognitive and global function was observed in comparison with baseline scores. The patients themselves appeared in favor of Oxiracetam. The drug tolerability proved to be very good for the whole duration of the treatment. The authors believe that Oxiracetam favorably 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 test and at the Attentional Matrix test.