BACKGROUND: Baseline staging in patients with primary cutaneous malignant melanoma (MM) is routine, but the diagnostic accuracy and the impact on clinical outcome are still unclear. OBJECTIVES: To evaluate the sensitivity and specificity of baseline staging in the early detection of regional lymph node metastases or distant metastases in patients with MM. METHODS: One hundred consecutive patients with MM of Breslow's tumour thickness over 1.0 mm were enrolled. All patients had an extensive baseline staging including physical examination, ultrasound (US) of the abdomen and regional lymph nodes, chest X-ray, whole-body positron emission tomography (PET) and sentinel lymph node biopsy. The sensitivity and specificity of detection of macroscopic or microscopic metastases in the regional lymph nodes or at distant sites were calculated for each method. RESULTS: Sentinel lymph node biopsy was positive in 26 patients. US detected two of 26 histologically tumour-positive sentinel nodes (sensitivity 8%, specificity 88%) and PET two of 26 (sensitivity 8%; specificity 100%). There were three lymph node metastases with a diameter > 4 mm. All of them were found suspect at physical examination. Two of them were detectable with US, two with PET, and all were identified with either US or PET. Nine patients had suspect findings at distant sites, which were all false positive on further investigation (specificity of the combined staging procedures 91%). At 18 (6-37) months' follow-up, five of 26 (19%) patients with a positive sentinel node and four of 74 (5%) of patients with a negative sentinel node had recurrent or progressive disease. CONCLUSIONS: The combination of physical examination and lymph node US detects the great majority of patients with macroscopic lymph node metastasis (approximately 3% of patients at baseline). Only 10% of patients who have a histologically tumour-positive sentinel node are macroscopically detectable. Altogether, approximately 25% of patients have a positive sentinel node biopsy, among 90% microscopic. The value of whole body staging at baseline remains limited, since distant metastases can hardly ever be detected. The survival benefit of baseline staging and surveillance in patients with cutaneous MM remains to be established by comparative prospective trials.