Mesoglycan is a preparation of natural glycosaminoglycans, containing mainly heparan sulphate and dermatan sulphate. A clinical trial was conducted to evaluate the efficacy and the tolerability of once-daily mesoglycan in 30 patients with clinical evidence of cerebrovascular insufficiency. Clinical effectiveness was assessed using psychometric and neurological scales: Sandoz Clinical Assessment for Geriatric Patients (SCAG); Parkside Behaviour Rating Scale Modified; Geriatric Depression Scale; and Anxiety Evaluation. Mesoglycan was given as a single oral once-daily dose of 100 mg for a period of 6 months. This treatment was shown to have positive effects on the cognitive and behavioural parameters evaluated. The effects on SCAG were already evident after 3 months' treatment and a significant improvement was observed after 6 months in those patients with a moderate to severe disease. During the treatment period only one patient suffered an adverse reaction attributed to the drug investigated.