Thermal interstitial microwave ablation comparison between swine breast tissue and breast phantom using a coaxial antenna was presented. Experimental protocol was composed by a radiation system and a thermometry system. Coaxial antenna works at 2.45 GHz, power apply during experiments was 10 watts for 5 minutes. Thermal sensors were placed next to the antenna, at 0.50 cm, 1 cm and 1.50 cm to the antenna. Data was stored every second in the course of microwave radiation. Thermal sensors next to the antenna present a mean variation of 0.48°C, at 0.50 cm to the antenna, average variation is 1.33°C, sensors placed at 1 cm have a mean temperature variation of 0.38°C, and finally average variation in sensors inserted at1.50 cm to the antenna is 0.09°C.