Malignant melanoma (MM) has a high metastatic potential even in small primary lesions, and an early distinction between localized and regionally/distally advanced disease is of major importance for the patients' treatment and, consequently, for their survival. Exploiting the fact that tyrosinase is a tissue specific enzyme which is only expressed in normal skin melanocytes and MM cells that invade the blood during metastasizing, the objective of our study was to optimise the nested RT-PCR assay for the detection of tyrosinase mRNA and, hence, to detect circulating melanoma cells (CMC) in whole venous blood of MM patients. Eighteen MM patients (stage III and IV, according to AJCC) and 8 healthy subjects were included in our study. Following optimisation of the procedure, the lowest detection limit of 10 MM cells per 1 ml of the blood was achieved. Tyrosinase mRNA was detected in 27.8% (5/18) of blood samples from MM patients and in none of the healthy volunteers. Preliminary results of this study suggest that the method is sensitive and specific to the CMC detection in the peripheral blood and may thus be helpful in determining the disease stage and, consequently, in planning treatment.