Eight red blood cell (RBC) Le(a-b-) individuals were selected from a series of patients with bladder or colon cancer. Defined by the presence or absence of alpha 1-4-L-fucosyltransferase activity in saliva, four of these patients were characterized as non-genuine Lewis negative [RBC Le(a-b-) with alpha 1-4-L-fucosyltransferase activity in saliva], and four as genuine Lewis negative [RBC Le(a-b-) with no alpha 1-4-L-fucosyltransferase activity in saliva]. Stainings of paraffin embedded formalin fixed tissue sections for Lea and Leb antigens were performed by means of an indirect immunohistochemical method on all malignant and benign tissue previously removed from these eight patients. Leb antigens were always expressed independently of both the Lewis and the secretor status of the individual. Lea antigens, on the other hand, showed a different staining pattern. Although primarily expressed in non-genuine Le(a-b-) individuals, Lea antigens were expressed in genuine Le(a-b-) individuals as well--to a limited extent, but still detectable. Thus, these findings seem to show that the Lewis antigen expression is tissue dependent, and it is not possible to predict tissue Lewis antigen expression by merely examining erythrocytes or saliva.