Percutaneous ethanol injection therapy (PEIT) has become widely used in the treatment of HCC. However, the indications for this method are limited by the toxicity of ethanol itself. Against this background, the authors turned their attention to the heat coagulation necrosis effect induced by boiled physiological saline (hot water) and devised percutaneous hot water injection therapy (PHoT) as a new local treatment method. PHoT was performed a total of 41 times in 13 patients (16 nodules) with HCCs measuring < or = 3 cm. Changes in AFP values, CT findings, angiographic findings before and after treatment, and histopathological findings of needle biopsy or resected specimen were investigated. AFP values decreased in all of the seven patients who initially showed high values. On CT, all lesions receiving PHoT became hypodense, with this change thought to indicate necrosis. Disappearance of the tumor stain was confirmed in the four patients in whom follow-up angiography was performed. In the six patients in whom needle biopsy was performed, disappearance and scaring of tumor cells were observed, while in the one patient in whom the tumor was resected, complete necrosis of the tumor was confirmed. PHoT, despite a small number of punctures, shows good anti-tumor effects, and has promise not only as a curative local treatment method for small HCCs but also in combination with TAE for large HCCs.