BACKGROUND Some randomized studies, mostly of short duration, have indicated that cholinesterase inhibitors (donepezil, rivastigmine and galantamine) may have a beneficial effect in Alzheimer's disease, vascular dementia and in dementia caused by Lewy body disease. The benefit of these drugs in clinical practice has not been satisfactorily documented. MATERIAL AND METHOD Literature collected regularly for many years supplemented by extensive non-systematic searches of Pubmed and Embase. RESULTS Only in a few placebo-controlled, double-blind, randomised studies were the patients followed for more than one year. Several clinical tests were performed, among them the Mini Mental Status (MMS)-test, which is the most commonly used test in clinical practice. The three cholinesterase inhibitors led to statistically significant results, although of limited clinical relevance, in various forms of dementia. INTERPRETATION Based on the results obtained it could be questioned whether the observed effects are of clinical significance. Only a small proportion of patients with Alzheimer's disease seem to benefit from the cholinesterase inhibitors tested, and it is difficult to predict who will in advance. Treatment should first be evaluated after 2-4 months and subsequently on a regular basis, and accepted clinical tests should be applied.