OBJECTIVE: To examine GPs' self-reported basic diagnostic evaluation of dementia according to the recommendations in multidisciplinary consensus guidelines and to analyse explanatory factors for GP performance. DESIGN: Postal questionnaire study, spring 1998. SETTING: General practice in Denmark. SUBJECTS: All 3379 GPs in Denmark. RESULTS: The questionnaire was completed by 75.1%. According to our Diagnostic Evaluation Index, 47.2% of the GPs were classified as conducting a good basic diagnostic evaluation of dementia, and tended to have the following characteristics: they conducted regular follow-up consultations with demented patients (odds ratio (OR) 2.4), they were inclined to state that all patients with possible dementia should undergo diagnostic evaluation (OR 2.0), they considered that the GP should play the major role in diagnostic evaluation (OR 1.7) and they believed their methods were adequate identify dementia (OR 1.7). Gender, attitude to development of clinical guidelines and being able to refer patients to specialists were not influential. CONCLUSION: We conclude that the previously reported reluctant attitude of GPs is now more positive.