It has been hypothesized that acetyl-L-carnitine has a cholinomimetic action. It is for this reason that it has been used in the therapy of Alzheimer's type senile dementia impairment. In the present controlled double-blind study the authors followed two randomized homogeneous groups of both sexes of 30 patients each, aged over 65 years and suffering from mild mental impairment. One group of patients underwent therapy with acetyl-L-carnitine, 2 g/day for three months, while the other group was treated with a placebo. The statistical evaluation of the results was carried-out using non-parametric methods (Friedman-Nemenyi two-way ANOVA). It was possible to affirm that the acetyl-L-carnitine treated patients showed statistically significant improvement in the behavioural scales, in the memory tests, in the attention barrage test and in the Verbal Fluency test. These satisfactory results confirm the therapeutic importance of acetyl-L-carnitine in the treatment of elderly patients with mental impairment, which could be related principally to acetylcholine defects.