Primary and metastatic liver cancers have a poor prognosis. At present, sonographically guided alcohol injection results in a partial reduction of cancer masses even if severe toxic effects (including pain and bleeding) are always present. For these reasons, a pilot study was started to evaluate the feasibility of an intralesional adoptive immunotherapeutic approach, using lymphokine-activated killer (LAK) cells and recombinant interleukin-2 (rIL-2). Nine patients (one with primary hepatocarcinoma and eight with liver metastases) entered the study. Four cycles of weekly injections of LAK cells (ranging from 2 to 9 x 10(8)) and 10(6) IU rIL-2 were performed percutaneously under ultrasonic guidance. In the same period, 3 x 10(6) IU rIL-2/day, for 24 days, was injected subcutaneously. All patients but one completed the therapy. Side effects were limited to grade 1-2 fever and were mostly related to rIL-2 subcutaneous injections. No patients complained of having pain during intralesional therapy. Two complete responses were detected. One partial response, four stable diseases, and one progressive disease were observed. One patient was not evaluable. These preliminary results suggest that sonographically guided intralesional adoptive immunotherapy of liver tumors is feasible, safe, and could offer promising therapeutic advantages in cancers for which conventional treatment is generally unsatisfactory.