Peroxidation of low density lipoproteins (LDL) may be involved in the development of atherosclerosis which is prevalent in patients with chronic renal failure and renal transplant recipients. We determined the copper ion catalyzed oxidation in vitro, vitamin E content, and chemical and fatty acid composition of LDL isolated from 38 patients with renal disease and 15 healthy subjects. Also the acute effect of hemodialysis treatment on LDL oxidation variables was tested. The lag time in conjugated diene formation during oxidation was significantly (P = 0.011) shorter in LDL from renal transplant recipients (66 min, N = 18) mainly due to significantly (P < 0.05) shorter times in women (47 min, N = 7), compared with healthy subjects (83 min, N = 15), patients on hemodialysis (91 min, N = 13) and patients treated by continuous ambulatory peritoneal dialysis (CAPD) (82 min, N = 7). The maximum rate and the extent of LDL oxidation were significantly (P < 0.01) lower in all patients with renal disease compared with healthy subjects. The triglyceride content of LDL was significantly (P < 0.001) higher in women with kidney grafts (7.3%) compared with levels in the corresponding men (5.3%) and healthy women (5.0%), and was correlated significantly with the lag time in LDL oxidation in renal transplant recipients (Spearmans r = -0.502, P = 0.034). The percentage oleic acid in LDL was significantly higher (P = 0.002) and the percentage linoleic acid was significantly lower (P = 0.046) in patients with renal disease, and may largely account for their lower rates and extent of LDL oxidation. Levels of the LDL oxidation variables and organic lipid peroxide content of LDL were not significantly different before and after hemodialysis and 24 hours later. These results suggest that LDL from women with renal transplants may be abnormally susceptible to oxidation possibly due to increased triglyceride content.