To go toward non-invasive melanoma analysis without the requirement of biopsy, in vitro and in vivo investigations have been performed with near-field microwave sensing techniques. Preliminary dielectric study has been carried out on different types of skin crushes: normal skin and skin with a subcutaneous B16 melanoma tumor. Extracted dielectric properties permits to clearly discriminate the two samples. Based on these results, in vivo investigations-have been performed on living mice, leading to a possible microwave-based detection of melanoma, which should now be confirmed with statistical measurements. The dielectric results are in agreement with the observation through immune-analysis of increased vascular density in the presence of a tumor, i.e. water content rise.