Malignant melanoma is a highly aggressive cancer with a poor prognosis due to resistance to radiotherapy and chemotherapy regimens. The mainstay of treatment remains DNA-alkylatingagent dacarbazine (DTIC). Fotemustine (FM), chloroethylnitrosourea agent, also has demonstrated significant antitumoral effects in malignantmelanoma. However, the resistance of melanoma cells limits their clinical application. In order to enhance the inhibition of melanoma cell growth, in this study, combined treatment of FM and DTIC with proton irradiation, was investigated. We analyzed the effects of combined treatment on HTB140 melanoma cell viability and proliferation. Significant inhibition of cell growth, especially cell proliferation, was obtained after treatment with protons and FM compare to single irradiation or drug treatment. Treatment with protons and DTIC has shown improved growth inhibition compare to appropriate single drug treatment, but not compare to irradiation as a single treatment.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200