Seven sural nerve biopsy specimens from patients with chronic uremia requiring dialysis were subjected to light and electron microscopy. Teased single fibers were examined for segmental demyelination and evidence of remyelination. Specimens were also examined by gas-liquid chromatography. Neuropathy is found histologically in patients without clinical peripheral nerve dysfunction, and the severity of pathological changes does not correlate with clinical or electrodiagnostic findings. Segmental demyelination, axon loss, wallerian degeneration, Schwann cell proliferation with formation of "onion bulbs," and remyelination were found. Gas-liquid chromatography showed significant differences in elution curves of sural nerves from patients with chronic renal disease when compared with those obtained from controls and patients with diabetic or alcoholic neuropathy. Clinical, pathological, and biochemical features suggest that neuropathy is, in part, caused by derangements in protein metabolism of Schwann cells.