Abstract: We estimated the diagnostic skill of clinicians managing melanocytic skin naevi by measuring the percentage of malignant melanomas, premalignant and potentially malignant naevi, in 1896 excised melanocytic lesions submitted to a pathology service over 11 weeks. They comprised 8 per cent. The percentage increased with age: 4 per cent in the under-40s, 17 per cent in those aged 40–59, and 30 per cent in those over 60, (P < 0.001, sex-adjusted). Although the percentage was twice as high in males (11 per cent) as females (6 per cent), after adjustment for age the difference was not significant. Invasive melanomas, 3 per cent of the total, were similar: 1 per cent were from under-40s; 7 per cent from those aged 40–59 years; and 14 per cent from those over 60. They comprised 4 per cent of lesions from males and 2 per cent from females. These trends may indicate poor specificity of clinical diagnosis, notwithstanding other reasons for removal of naevi (cosmetic), particularly among patients under 40, and females.