Leucocyte-function-associated antigen-3 (LFA-3) is a cell surface glycoprotein involved in T-cell/target cell interaction. The expression of LFA-3 on the cell surface was found to be inevitably associated with the expression of HLA molecules. Loss of LFA-3 or HLA proteins on tumour cells might result in ineffective T-cell/target cell interaction and a failure of immunological tumour surveillance. Immunohistochemistry revealed that LFA-3 is expressed in normal colonic epithelium; however, in a minor fraction of colonic adenomas and in 50.3% of colorectal carcinomas LFA-3 expression was reduced or even absent. To investigate whether the presence or absence of LFA-3 in colorectal carcinomas influences the relapse rate and time of tumour-related death, 149 patients who underwent putatively curative surgery were surveyed for a maximum of 65 months (mean 48 months). In contrast to the prognostic role of tumour stage and grade, the presence versus absence of LFA-3 was not correlated with recurrence or survival. Regarding survival and growth of residual tumour cells after potentially curative resection of the initial tumour burden, we conclude that the status of LFA-3 expression in colorectal carcinoma seems to be irrelevant in vivo.