Human lymphokine-activated killer (LAK) cells were prepared by culturing normal peripheral blood mononuclear cells (PBMC) for 4 days with or without added recombinant interleukin 2 (rIL-2) and assayed for anti-tumor activity against established squamous cell carcinoma lines of the head and neck (SCCHN) in vitro and in nude mice. The results showed that LAK cells had a stronger cytotoxicity than control cells to different SCCHN in vitro. In vivo, LAK cells almost completely inhibited the growth of HEP-2 tumor in nude mice and resulted in an inhibition rate of 81.6% (P < 0.01 with control cells). Our data indicate that LAK cells may be useful in the treatment of patients with head and neck tumors.