Heat shock proteins (HSPs) are known to be of crucial importance in host-tumor interactions. The goal of this study was to determine whether there was an increase in HSP expression in a patient suffering from unresectable hepatocellular carcinoma treated with percutaneous radiofrequency (RF) ablation. Immediately before RF ablation, a computed tomography (CT)-guided core needle biopsy (diameter, 18 gauge) was obtained from the tumor. The RF ablation was then performed using a saline-perfused RF ablation system (diameter of RF electrode, 15 gauge; ablation time, 10 min). Twenty-four hours after tumor ablation, core needle biopsy was repeated, and biopsy specimens were obtained from the residual tumor margin visible on contrast-enhanced CT. For both procedures, no side effects or clinically relevant complications were observed. The specimens were mapped by immunohistochemistry, determining the cellular expression of HSP 70 and HSP 90. After RF ablation, in the cytoplasm and at the tumor cell surface, an 8-fold increase in HSP 70 and a 1.2-fold increase in HSP 90 was observed, respectively. In the cell nucleus, the HSP 90 expression before RF ablation was 10%, and decreased to 0% after RF ablation. We have demonstrated that, following RF ablation, cellular expression of HSP 70 and HSP 90 in hepatocellular carcinoma is increased. We further suggest that routing of HSP 90 from the nucleus to the cell surface occurred after RF ablation. This may be of relevance in further therapeutic anti-tumor strategies.