Receptors for the Fc part of IgG (Fc gamma R) are expressed in three forms on peripheral blood lymphocytes. The presence of the releasable form (Fc gamma R(REL.)) as well as of the two nonreleasable forms with lower (Fc gamma R(LOW)) and higher (Fc gamma R(HIGH)) cellular avidity was correlated with survival in 63 patients with B-cell chronic lymphocytic leukemia (B-CLL). High percentage of cells with Fc gamma R(LOW) as well as high "absolute" number of cells carrying the two nonreleasable forms of Fc gamma R were connected to unfavorable prognosis. Combining these three parameters, an Fc gamma R constellation was defined which pointed to a favorable prognosis (in 24 patients) when all three parameters were low, but detected short survivors when all three data were high (in 14 patients). The Fc gamma R constellation was capable of identifying patients with better or worse prognosis within groups that were homogeneous regarding some other known prognostic factors. Fc gamma R constellation as a prognostic factor was shown to be independent of age, sex, and Rai and Binet stages, but it was found to be connected with the total tumor mass score (TTM). The three forms of Fc gamma R on B cells might reflect stages of B-cell activation. Differences in Fc gamma R constellations between patients with B-CLL would thus correspond to differently activated B-cell clones with variable prognosis.