A double-blind, placebo-controlled trial was carried out in 97 elderly patients with age-related mental deterioration to assess the efficacy of ergoloid mesylates in improving their symptoms. Patients were allocated at random to receive either 4.5 mg ergoloid mesylates per day or a matching placebo tablet and were followed-up for 6 months after the start of treatment. Clinical examinations were performed by the doctor, using the EACG rating scale (a French version of the Sandoz Clinical Assessment Geriatric scale), and by the nurse, using the NOSIE scale, when patients entered the trial and repeated after 2, 4 and 6 months. Changes in the factors (symptom groups) covered by these scales were subjected to statistical analysis. After 6-months' treatment, a statistically significant difference in favour of the ergoloid mesylates group was observed for cognitive deficits (p less than 0.05), anxiety and mood depression (p less than 0.01), unsociability (p less than 0.01), retardation (p less than 0.05) and irritability (p less than 0.001). Treatment was very well tolerated. It was also observed that there was a progressive increase in efficacy throughout the trial; this indicates that treatment with ergoloid mesylates in patients with mental deterioration should be long-term.