Abstract The expression and release of adhesion molecules by acute myelogenous leukemia (AML) blasts was investigated in vitro. For most patients AML blasts expressed relatively low levels of membrane-bound l-selectin and Intercellular adhesion molecule 1 (ICAM-1), but their soluble forms were detected in the supernatants for the majority of patients when AML blasts were cultured in vitro. These in vitro levels of s l-selectin and sICAM-1 were considerably lower than the normal serum levels. Divergent and relatively small alterations in s l-selectin and sICAM-1 levels were usually observed when exogenous growth factors were present during AML blast culture, whereas increased s l-selectin levels were observed after coculture of AML blasts and normal leucocytes. e- and p-selectin were neither expressed nor released by AML blasts. We conclude that AML blasts are a source of soluble adhesion molecules.