Inoculation of plasmid DNA vectors encoding immunogenic proteins induce humoral as well as cell-mediated immune responses. Protection against challenge with pathogens has provided protective immunity in several instances in animal models. (1,2). DNA vaccines allow the simultaneous expression of antigens and immune-stimulatory cytokines via an internal ribosomal entry site (IRES). Here we describe the construction of a DNA vaccine against malignant melanomas using: (i) the tumor-associated antigen gp100 (or pmel17), known to be over-expressed in many malignant melanomas (3,4), and (ii) the granulocyte macrophage stimulating factor (GM-CSF) which has been shown to have a stimulatory effect on humoral and cellular immune responses (5).