Registrations of clinical signs of neuropathy, quantified according to a fixed protocol, and determinations of vibratory perception thresholds and nerve conduction velocities (NCV) were performed in 22 patients treated with hemodialysis (HD) and in 21 patients treated with continuous ambulatory peritoneal dialysis (CAPD). Measurements were made at the start of dialysis and during a follow-up period of about 30 months. Motor NCV decreased in both groups; vibratory thresholds increased markedly in the CAPD patients, but not in the HD patients; and the clinical signs worsened in the HD patients, but not in the CAPD patients. The difference in outcome of the clinical signs during HD and CAPD was not of such a magnitude that one of these dialysis forms should be preferred before the other as regards neuropathy. We conclude that peripheral neuropathy may deteriorate during both HD and CAPD, but in significantly different ways, indicating that several pathogenetic mechanisms are probably involved in uremic neuropathy.