Human autologous tumour-specific cytotoxic T lymphocytes (CTL) were generated from peripheral blood on small formalin-fixed paraffin-embedded sections of a gastric cancer. The CTL killed live target cells at an effector/target ratio of 1 within 24 hours and showed the same target specificity as those induced on live cancer cells. The killing activity of the CTL lasted for more than four months in culture and was inhibited by antibodies against CD8 and MHC-class I. These results suggest that adoptive immunotherapy of tumours will be possible with CTL induced on a stable source of tumour antigen.