Optimal conditions have been defined to grow primary cultures of malignant melanoma suitable for in vitro pharmacological studies. A feasibility of primary cultures was observed in 60% of 62 clinical melanoma lymph node metastases. The neoplastic nature of the cells grown in culture, as assessed by the highly specific monoclonal antibodies anti-S100 and HMB45, was confirmed in 100% and 65% of the cases, respectively. Flow cytometric analysis showed a high stability of DNA content profiles observed in clinical samples through all the methodologic steps used to obtain in vitro cultures. The intertumor variability of the degree of the antiproliferative effect of melphalan and its relation with DNA interstrand cross-links (DNA ISC) provided preliminary evidence of the reliability of the experimental system for in vitro evaluation of anticancer drug activity.