The majority of patients with primary and secondary tumours of the liver cannot be treated curatively by surgery. The treatment of these patients with radio-frequency thermoablation using perfused needle applicators (wet electrodes) was evaluated in a feasibility study. Patients with primary and secondary tumours of the liver and contraindications against surgery or LTX were included into the feasibility study. RFA was performed percutaneously under ultrasound guidance. The patients were followed up sonographically and by computed tomography. 20 patients (9 male, 11 female) with 35 lesions were treated with RFA. 12 patients (22 tumour locations) suffered from HCC and 8 patients (13 tumour masses) had liver metastases (colorectal, breast, pancreas, carcinoid). The median age was 65.6 years (36 to 83 years). The median tumour size was 33.5 mm. 59 RFTA applications (1.7 applications per tumour mass) were performed. The mean duration of RFTA per patient was 16.2 minutes. During the procedure isotonic saline was injected at a mean flow rate of 6.63 ml/min. All patients received local anaesthesia. In 33 sessions an additional analgosedation was necessary (average dose 63.8 mg Pethidine and 1.4 mg Midazolam). In 2 cases a reduction of the haemoglobin level, occurred, necessitating a blood transfusion. 3/4 of the treated metastases could be eradicated completely. Within a median follow-up of 145 days no intrahepatic local recurrence but 4 distant metastases occurred. 2/3 of the treated HCC could initially be brought into complete remission (CR). After a median follow-up of 329 days 5 of the 8 initially successfully treated patients with HCC were still in complete remission. In 3 cases an intrahepatic local recurrence developed. RFA with wet electrodes is a safe, effective and inexpensive treatment for primary and secondary tumours of the liver, measuring less than 4 cm in diameter.