CD3+ CD56+ NKT-like cells have been shown to produce substantial amounts of pro-inflammatory cytokines and to mediate lysis of malignant cells. Using flow cytometry, we evaluated the absolute NKT-like cell count in peripheral blood from individuals in a reference population and the median number was 0.085 x 10(9)/l. The average number of NKT-like cells in patients with disseminated cancer was 2.65 fold higher than in the reference population. The number of CD3+ CD56+ cells in solid tumour patients who achieved complete remission was comparable to the reference population. In breast cancer patients with initially (prior to therapy) increased number of NKT-like cells, we observed a trend toward longer disease-free survival. Thus we conclude that CD3+ CD56+ NKT-like cells have potential to suppress tumour evasion and are expanded in peripheral blood of some epithelial tumour patients.