Dermal tissue characterization based on dielectric properties can be utilized as a non-invasive method for diagnosis of skin cancers. To enable such technology, there is a need to develop techniques that can rapidly and accurately collect the dielectric properties of the skin tissues. Therefore, the current measurement techniques and tools has to be optimized for skin cancer detection. To this end, this study presents dielectric property measurements with open-ended coaxial probes having small apertures customized for detection of skin cancer. Relative permittivity and conductivity of rat skin tissue is characterized with open-ended coaxial probes with outer diameters of 0.9mm and 0.5mm between 0.5GHz-6GHz and the measurement results are compared with the traditional probes having diameter of 2.2mm. The results agree well with the reported literature data.