BACKGROUND: The GP often has a primary function in assessing pigmented skin lesions in Denmark. No data are available on the diagnostic accuracy of this process. OBJECTIVE: We aimed to study the sensitivity, specificity and positive prognostic value of the diagnosis made by 27 trained or trainee GPs. METHOD: We tested the diagnostic accuracy of the viewing of colour slides of pigmented skin lesions under standardized conditions at a seminar on skin cancer. Diagnostic accuracy was determined only for the clinically relevant diagnosis of benign or malignant. RESULTS: The median diagnostic accuracy (sensitivity) for the group as a whole was 0.75 (95% CI 0.65-0.80), the specificity was 0.70 (95% CI 0.68-0.79) and the positive predictive value 0.70 (95% CI 0.62-0.77). CONCLUSION: These values are comparable with previously published figures for trainee dermatologists, and it is therefore concluded that ongoing interest rather than basic training is the major determinant for clinical acumen.