The effect of supraphysiological thermal therapy on tissue viability was investigated in an AT-1 Dunning rat prostate tumor model. After a thermal protocol was performed with concurrent temperature measurements, an in vivo-in vitro assay was used to assess cellular survival based on known thermal history and tetrazolium dye (TTC) and histology was used to evaluate overall tissue response 1, 3 and 7 days post ablation. The cellular study showed that survival gradually dropped to 0 with an increase in predicted injury (Ω) from 0.1 to 1. TTC analysis showed significant drop in enzyme activity and morphometry of histology revealed a significant increase in coagulative necrosis (p<0.01 for both studies) after each of 1, 3 and 7 days compared to sham tissue. These results show that controlled thermal destruction can be obtained in AT-1 prostate tumor using thermal therapy with no cellular survival at temperatures >47 °C for times≥a minute.