We have studied ras p21, c-myc p62 and c-erbB-2 oncogene expression in fourteen Greek patients with NON AIDS Mediterranean Kaposi's sarcoma using immunohistochemical analysis. Elevated expression of ras p21 expression was observed in all 14 cases studied (8 of which had intense levels of staining), whereas expression of c-myc and c-erbB-2 was less frequent, (6 out of 13 cases tested showed elevated c-myc expression and 6 out of 13 showed elevated c-erbB-2 expression). This report indicates that aberrant ras p21 oncogene expression is a feature of Kaposi's sarcoma and may be important in the early stages of this disease.