The following guidelines are recommended in the management of malignant melanoma. An excisional biopsy is the appropriate diagnostic procedure for a skin lesion suspected of being a melanoma. The advised margin for diagnostic excision is 2 mm of macroscopically normal skin around the lesion; the margins for therapeutic excision are 1 cm of normal skin for a lesion with a Breslow thickness of < 2 mm and 2 cm when the Breslow thickness is > 2 and < or = 4 mm. A margin of at least 2 cm also appears to be justified for thicker melanomas. Elective lymph node dissection is not recommended. Sentinel node biopsy appears to be a promising method to detect occult metastases in the regional lymph nodes. If regional lymph node metastases are present, therapeutic regional lymph node dissection must be conducted. Isolated regional perfusion is indicated for inoperable tumour growth in an extremity. Radiotherapy can be applied palliatively or postoperatively (if non-radical resection is suspected). Adjuvant systemic therapy is still experimental. There is no standard treatment for patients with haematogenic metastasis and they should be entered in trials whenever possible. A follow-up period of 5 years is sufficient for patients with a melanoma of < or = 1.5 mm Breslow thickness and of 10 years when the Breslow thickness is > 1.5 mm. The patients should be actively involved in the follow-up (inspection, palpation). Regular routine blood tests and radiological examinations are not considered to be worthwhile. There is no evidence that the growth of micro-metastases is stimulated by hormonal changes during pregnancy or contraceptive pill use. Excessive exposure to ultraviolet radiation should be discouraged.