A seven-point scoring system has been adopted by the Cancer Research Campaign to help non-dermatologists recognize melanoma (MM). Its value is reviewed in the light of increasing referrals of pigmented lesions. One-hundred and ninety-five patients (M:F, 43:152; mean age = 43 years, s.d. = 19) were asked whether their lesions possessed the seven points before diagnosis. The dermatologist assessed the signs. Six patients were unable to comply and some had multiple lesions; thus, 216 lesions were fully assessed by patient and dermatologist, and six by the dermatologist alone. Histology was obtained where appropriate. There were eight MMs, 95 naevi, 80 seborrhoeic warts, three dysplastic naevi, and 36 other lesions. Seven of the eight MMs were diagnosed clinically; the other was biopsied because of suspicious features and was a nodular MM. Four lesions suspected to be MMs proved benign. The predictive value (PV) of a clinical diagnosis of MM was 64% and of non-MM was 99%. Using accepted cutpoints for the seven-point system (refer if score greater than or equal to 3) patients' scores gave a PV for MM of 7% and for non-MM of 99%. Two MMs scored less than three. Dermatologists' scores gave a PV for MM of 8% and for non-MM of 99%. One MM scored less than 3. Univariate analyses showed that enlargement (P less than 0.05), dermatologists' assessments of an irregular margin (P less than 0.001), size (P less than 0.05) and pigmentary irregularity (P less than 0.05), and patients' assessments of size (P less than 0.05) were statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)