BACKGROUND Reports published in 1996 concerning the protein MIA proposed it as a useful tumor marker for patients suffering from malignant melanoma. Therefore we systematically started to measure MIA levels in patients with malignant melanoma. It was and still is questionable whether MIA in the serum of melanoma patients is a reliable tumor marker in terms of course of disease, therapy-monitoring and prognostic value. Previous studies have already confirmed the specifity of MIA as a tumor marker for malignant melanoma. METHODS Using an ELISA- System, we examined over 830 blood samples of 326 melanoma patients. The cut-off was determined at 9.8 ng/ml. RESULTS 5.6% (n = 17) of melanoma patients at stage I/II (n = 302) showed increased MIA levels, whereas at stage III/IV (n = 5/n = 19) high levels were found in 60.0% and 89.5% respectively. Patients at stage III/IV with MIA levels below the cut-off turned out to be the ones after metastatic surgery, irradiation or chemotherapy. None of these patients developed further metastases during follow-up, just as patients at stage I/II without increased MIA levels. After a distinct rise of MIA levels, metastases could be detected at the same time or shortly after. On the other hand we saw decreasing levels after or during therapy. CONCLUSIONS Our data showed that MIA is a suitable serum marker to detect metastases and to monitor course and therapy of disease. The prognostic value (increased MIA levels at stage I/II), however, requires further investigation.