The early detection and diagnosis of dementia is gaining in importance both for medical research and for individual case management. Here, a key part can be played by general practitioners, who are in contact with most of the affected old people and well placed to observe any signs of mental deterioration. A study in Mannheim, Germany, is reported, in which all contacts with over-65-year-old patients during one month were documented in each of 24 practices, and each patient's level of memory and cognitive functioning was assessed by his or her own doctor. A stratified subsample of patients in 21 of the practices was examined by the research team, using a standardized interview and test procedure. The findings indicate a greater accuracy of case recognition than has been reported in previous studies. In screening the interview subsample, the practitioners achieved a sensitivity of 92% and a specificity of 76%, identifying most of the mild as well as the severe cases. These results emphasize the potential importance of general practice for the early detection of dementia, and suggest that more attention should now be directed towards the clinical prognosis and management of cases presenting in the primary care setting.