In order to investigate the size variation of neoplastic B cells (NBC) from lymph nodes of patients with B-cell lymphomas (BCL), we carried out two-dimensional analysis by flow cytometry (FCM) using the forward light scatter (FLS) and the fluorescence intensity (FI) of surface immunoglobulin light chain (sIgL). NBC were identified as having the homogeneous characteristics of both FLS and tumor-restricted sIgL (kappa or lambda). The FLS variation of NBC was then analyzed using CD3+ T-cells as a scale control. The results closely coincided with the cell types determined by the pathologic diagnosis. Secondly, we used FCM to investigate how strongly NBC express VLA-4 alpha and LFA-1 alpha, which seemed to play important roles in neoplastic follicle formation. The expression intensities of these molecules were classified into three grades (-, + & ++). The results were presented in the order of VLA-4 alpha and LFA-1 alpha; follicular 8/15 (++/++), 6/15 (++/+), 1/15 (+/++), partially follicular 3/5 (+/++), 2/5 (+/+), diffuse 2/16 (++/-), 6/16 (+/++), 8/16 (+/+), B-CLL 8/8 (-/+ or -). These findings suggest that follicular lymphomas are phenotypically distinguishable from diffuse lymphomas.