The proposed research is centered around studies of the electronic properties of the pigment melanin and how these properties relate to the preferential destruction of pigmented tissues. As amorphous semiconductors the melanins provide the most relevant model for studying biological semiconductivity and the role played by high dielectric solvents (e.g, H2O) as well as the doping effects of various drugs (e.g., chloropromazine, diethylamine) which are known to effect the electronic properties of these pigments. The various properties of the pigments and other biological semiconductors will be investigated using conductivity measurements, threshold switching and stimulated conductivity techniques as well as microwave time domain reflectrometry which simultaneously measures dielectric spectra, polarization and relaxation spectra as well as bulk conductivity. The information gained from the molecular electronic properties will then be used as guidelines for experimental in vitro treatment of cultured melanoma cells with combinations of drugs and physical agents such as ultrasound. Experiments will be carried out to separate the non-thermal, electronic and mechanical, and thermal effects. Finally limited trials will be carried out to determine the efficiency of these treatments in patients with multiple superficial nodules of human malignant melanoma.