Polymorphonuclear leukocytes (PMNs) adhered tightly to glomeruli with immune complex in vitro in the cryostat sections of nephritic kidneys. The sections were incubated with PMNs for 40 min at 37 degrees C. The kidneys were obtained from rats with experimental glomerulonephritis induced by the prolonged administration of bovine serum albumin. This PMN adherence occurred when PMNs were suspended in fresh rat serum (one-step method) or the sections were treated with the fresh serum prior to the incubation with PMNs (two-step method). However, this adherence was inhibited by treatment of PMNs with trypsin to destroy their complement receptors. The inhibition was concomitant with the decrease in the percentage of rosette-formation by complement-coated zymosan particles. In addition, the adherence was markedly suppressed in both methods using decomplemented serum with zymosan. The aggregated rabbit gammaglobulin opsonized with fresh serum also inhibited the binding of PMNs to the glomeruli by the occupation of the complement receptors on PMNs. These findings indicated the important role of complement components on the glomeruli with immune deposits and complement receptors on PMNs in the PMN adherence.