Introduction and aim: Results from various laboratories using different experimental approaches indicate that heat shock proteins (hsp) are powerful inducers of anti-tumor immune responses. Our group is testing the DNA-HSP65 vaccine in murine tumor model, since results of Phase I Clinical Trial in squamous cell carcinoma bearing patients seem really promising. Methods: For this purpose, female C57Bl/6 mice were subcutaneously injected with 5 x 10⁴ B16F10 cells of murine melanoma linage. After 10 days, the animals were treated by intratumoral injection with a single dose of DNA-HSP65 (100 µg), vector (100 µg) or saline as control. Nine days after the end of treatment, the animals were killed and tumors were removed and weighted. Tumor samples were divided in three parts: (1) for histological studies; (2) to detect hsp65 mRNA by RT-PCR and (3) to evaluate the infiltrating cells by FACS. Survival rates of mice were determined in order to check if our vaccine could enahnce their life time. Results and Discussion: Our preliminary results showed that tumors of animals treated with DNA-HSP65 were smaller (0,135 ± 0,125 g) when compared with the vector (0,808 ± 0,581 g) or saline (0,541 ± 0,242 g) treatments. Histological analysis (HE) showed a higher incidence of tumor necrosis in vaccine-treated animals. Moreover, we observed an increase in the immune cells infiltrating the melanoma tumors in these animals (CD4+/CD44+; CD8+/CD44+; CD4+/CD25+ and NK cells). The evaluation of survival rates demonstrated that although all mice died before 45 days, the animals treated with a single dose of DNA-HSP65 showed a significant enhancement in the survival rate when compared with control group. Conclusions: Our results suggest a potential stimulation of the immune response against this type of cancer by the DNA-HSP65 vaccine, as evidenced by tumor necrosis, immune infiltrating cells and enhancement in survival rate. Based on this preliminary study, our next goals are to clarify the mechanisms of immunemodulation by this vaccine and to test other formulations to optimize its action.