In 63 patients with B-cell chronic lymphocytic leukemia the expression of three recently described forms of the IgG Fc receptor (FcR) was correlated with other cell surface structures detected by rosetting or monoclonal antibodies. In 7.4% of the more than ten thousand statistical investigations paired linear or non-linear correlations were found. Partial correlation technique eliminating the effects of the varying lymphocyte count still resulted in a high number (169) of correlations fulfilling the unusually strict criteria applied. Using a stepwise multiple regression method to create mathematical models describing the expression of the different forms of FcR it was shown that (1) expression is predominantly a function of certain B-cell markers, (2) models change with the progression of the disease, and (3) B cells in B-CLL have an activated phenotype shown by the presence of the releaseable form of FcRII, an early activation marker of B cells.