Background: Antiphospholipid antibodies have been found in the sera from patients with idiopathic and secondary glomerulopathies, mainly related to lupus. No special attention has been devoted to idiopathic membranous nephropathy, a glomerular disease with a high frequency of thrombotic complications, particularly of the renal vein. Aim: To study the presence and significance of antiphospholipid antibodies in idiopathic membranous nephropathy. Material and methods: Anticardiolipin and anti-ß2-glycoprotein-I IgG antibodies were measured in serum samples from 21 patients with idiopathic membranous nephropathy (age range 11-75 years, 5 female). The medical records of 20 of these patients were reviewed, looking for vascular complications and nephrological evolution during a follow-up period that ranged from two to 277 months. Results: Five patients had anticardiolipin antibody titers over the cutoff for normal values, and two others were positive for anti-ß2-glycoprotein-I, without cross-reactivity. There was no difference in the incidence of thrombotic complications in the renal vein, or other locations, between these seven patients and the remaining patients. No differences in the clinical course of the nephropathy were detected either. Conclusions: Antiphospholipid antibodies may be found in patients with primary membranous nephropathy. They are not related to thrombosis or a worse evolution (Rev Méd Chile 2005; 133: 287-93)