Background. Cardiovascular disease is the most common cause of morbidity and mortality in patients with chronic renal failure. Glomerulonephritic patients have an increased risk for cardiovascular disease, but its etiology is unclear. It is known that an increase in oxidizability of apolipoprotein B-containing lipoproteins has a key role in the initiation of atherosclerosis, and paraoxonase enzyme activity particularly has a preventive role against atherosclerosis. The aim of the present study was to evaluate the oxidizability of apolipoprotein B-containing lipoproteins, serum, and urinary paraoxonase/arylesterase activities in g] omerulonephritis patients who had normal lipid parameters and creatinine levels. Methods. Thirty-two patients with glomerulonephritis and 22 healthy controls were included in this study. A total of 32 patients (including nine with membranous GN, eight with immunoglobulin A nephropathy, eight with mesangial prolifferative GN, five with focal-segmental glomerulosclerosis, one with diffuse proliferative GN, and one with minimal chance disease having biopsy proven GN) were enrolled into the study. We compared serum and urinary paraoxonase, arylesterase, serum lipids, urea, creatinine, hemoglobin, total protein and albumin values between groups. Results. Serum urea, creatinine, total protein, albumin, uric acid, hemoglobin, and lipid parameters were similar in the glomerulonephritis and control groups (p > 0.05). PON1 activity was significantly lower in GN group nan controls, but there was no statistically significant difference on arylesterase activity between groups. Oxidizability of apolipoprotein B-containing lipoproteins was significantly higher in GN group than controls. Conclusion. Our study shows that the findings of normal serum levels of creatinine, lipids, and protieins increased the oxidizability of apolipoprotein B-containing lipo-proteins, and any decrease in PON1 activity in patients diagnosed with GN should be considered important. Hence, the immediate commencement of preventive as well as curative treatment in other to avoid the risk of cardiovascular and renal problems would be a correct approach.