In addition to cognitive performance tests, the assessment of activities of daily living (ADL) is becoming increasingly important in diagnosing and following up dementia. Therefore, we compared results obtained from ADL informant and self reports and from the SKT short test for assessing deficits of memory and attention. Data were available from a total of 193 elderly subjects in different stages of cognitive decline (GDS stages 1-5). First, we determined for each GDS group separately the numbers of subjects assessed as being impaired by each of the three methods alone as well as in combination. Furthermore, the contribution of the two ADL measures, the SKT total score, age, depression and education in the prediction of the global severity assessment according to GDS was evaluated. Finally, the influence of the latter three variables on the ADL and SKT results was estimated by existing correlations. In GDS stage 2, ADL self rating was the only approach revealing impairment with a majority of patients. The number of patients assessed as being impaired by ADL informant ratings and the SKT only increased after GDS stage 2. Analyses of patterns of impairment showed that 66% of subjects in GDS stage 1 were rated as unimpaired by each of the three methods. Of patients classified as GDS 4 and 5, 85% and 92% respectively were unanimously rated as impaired. In GDS stages 2 and 3 a great heterogeneity of patterns was found. In a logistic regression model predicting clinically manifest dementia symptomatology (GDS 4 + 5 vs GDS 1 + 2 + 3) the SKT and ADL informant ratings were included. In a second model predicting membership in a group without cognitive impairment (GDS 1 + 2) or in a group suffering from mild cognitive impairment (GDS 3) self-rated ADL and age were additionally entered. Especially for an early diagnosis of dementia, on the basis of the study results the usage of different assessment methods (ADL informant rating, ADL self rating, psychometric test) is suggested.