The cognitive and behavioral effects of oxiracetam therapy during long-term treatment in patients with dementia of Alzheimer type (DAT) and multi-infarct dementia (MID) were studied in comparison with a historical control group. Twenty DAT/MID outpatients, aged 54-86 years, received oxiracetam (800 mg twice a day) for a period of 6 months. Another 20 DAT/MID outpatients, aged 67-85 years, were selected from our clinical records in order to obtain a control group of patients matched for age, sex, diagnosis, baseline Mini Mental State Examination (MMSE) score and follow-up duration. All the patients were diagnosed as having mild to moderate degrees of dementia as defined by a baseline MMSE score between 14 and 24. The patients of both groups underwent, both at baseline and after 6 months, the following neuropsychological tests: MMSE, Idiopathic Cerebral Dysfunction Scale, Babcock Test, Gibson Spiral, Toulouse-Pieron Test. Statistical analysis of experimental data demonstrated that at baseline the two groups were comparable. At the end of the study period the oxiracetam group scored significantly better on the majority of the tests evaluating memory, attention, orientation, concentration and psychomotricity than the control group, in which a worsening trend was seen on the whole. No side effects were seen during oxiracetam treatment. The present study, showing positive clinical findings after long-term oxiracetam therapy in controlled conditions, confirms that this drug can be a useful pharmacological treatment for mild to moderate degrees of dementia.