Patients at advanced stage of colorectal cancer with liver metastases have been treated with deep hyperthermia alone or in combination with chemotherapy (5-FU + FA + MMC). Hyperthermia was achieved by arrangements of capacitive electrodes with a radiofrequency field of 13.56 MHz (RF-DHT). This prospective open single-arm clinical study with 80 patients suffering from liver metastases from colorectal cancer gives some first hints, that deep RF-hyperthermia alone may have a substantial beneficial effect on overall survival time of patients with liver metastases from colorectal cancer. Long lasting no-change, partial and even some complete remissions could be observed. The overall median survival time from progression of metastases or relapse was 24.5 months and survival rates at 1, 2 or 3 years from first diagnosis of metastases or progression were twice as high as expected from patients treated with chemotherapy. The combination of hyperthermia with delayed chemotherapy did not change overall survival time. These encouraging results deserve to be confirmed in randomized clinical studies.