Ten patients with nondialyzed chronic renal failure (CRF), 14 receiving continuous ambulatory peritoneal dialysis (CAPD), 16 receiving hemodialysis (HD), and 10 normal controls (NC), were evaluated. Levels of Fas antigen (CD95), scavenger receptors (CD36 and CD68), and tumor necrosis factor-receptor 2 (CD120b) on monocytes were measured using flow cytometry. All patients showed lymphocytopenia, and monocyte counts were decreased in those with CRF. Fas levels were higher in patients receiving HD than the others, and were higher in the CRF and CAPD groups than in controls. CD120b levels were similar to those of Fas. Monocyte CD36 levels in the dialysis groups were significantly higher than in the CRF and NC groups. CD68 was also significantly elevated in HD patients. Fas levels were positively correlated with those of CD120b and CD68. The patient groups showed higher levels of apoptotic markers and scavenger receptors, combined with activation of the TNF-alpha system, especially in patients receiving HD.