Background. Aspirin has a beneficial role in prevention of cardiovascular and thromboembolic events. Patients may experience thromboembolic events despite aspirin treatment, a phenomenon called aspirin resistance. We evaluated the frequency of aspirin resistance and its correlation with clinical and biochemical parameters among patients with nephrotic syndrome (NS). Methods. A total of 83 patients (50 males, 33 females, age range 18-79 years) with NS using aspirin 100 mg/day were included in the study. Demographic information and aetiology of NS based on the histology of a renal biopsy were recorded for each patient. Blood samples were drawn to investigate the association of aspirin resistance with inflammation and thrombotic risk factors. Aspirin resistance was defined as a normal collagen/epinephrine closure time <159 s using a platelet function analyzer (PFA-100). Results. Aspirin resistance was determined in 51 patients (61.4%). The number of patients exposed to azathioprine therapy was significantly higher in the aspirin-sensitive group (P = 0.043), whereas patients exposed to cyclosporine therapy were significantly higher in the aspirin-resistant group (P = 0.017). More patients in the aspirin-resistant group were on angiotensin-converting enzyme inhibitor therapy compared with the aspirin-sensitive group (P = 0.024). The aspirin-resistant group showed significantly higher serum low-density lipoprotein cholesterol (LDL-C) (151 ± 47 versus 104 ± 21 mg/dL; P < 0.001), triglyceride levels (192 ± 116 versus 134 ± 82 mg/dL; P = 0.015) and glomerular filtration rates (91.8 ± 43.0 versus 74.0 ± 35.6 mL/min/1.73m 2; P = 0.044) compared with the aspirin-sensitive group. In multivariate analysis, LDL-C was the only parameter associated independently with aspirin resistance [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.06; P = 0.004]. Conclusions.A significant number of patients with NS are resistant to aspirin therapy. Serum LDL-C level is closely associated with aspirin resistance in NS. © 2011 The Author.