The clinical relevance of heparin-induced antibodies (HIA) in the absence of thrombocytopenia remains to be defined. The aims of this study were (i) to determine the prevalence of HIA in patients treated by dialysis, (ii) to determine the prevalence of thrombocytopenia and heparin-induced thrombocytopenia (HIT), and (iii) to test whether HIA are associated with adverse outcomes. Sera from 740 patients treated by hemodialysis (HD, n=596) and peritoneal dialysis (PD, n=144) were tested for HIA (IgG, IgA or IgM) by masked investigators at approximately six months after enrolment in the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) study. We assessed, with time-to-event Cox proportional hazards models, whether the presence of HIA predicted any of four clinical outcomes: arterial cardiovascular events, venous thromboembolism, vascular access occlusion and mortality. HIA prevalence was 10.3% overall. HIA positivity did not predict development of thrombocytopenia or any of the four clinical outcomes over a mean follow-up of 3.6 years, with hazard ratios for arterial cardiovascular events of 0.98 (95% confidence interval 0.70-1.37), venous thromboembolism 1.39 (0.17-11.5), vascular access occlusion 0.82 (0.40-1.71), and mortality 1.18 (0.85-1.64). Chronic intermittent heparin exposure was associated with a high seroprevalence of HIA. In dialysis patients these antibodies were not an independent risk factor for cardiovascular events and mortality. Our data do not suggest that dialysis patients should be monitored for HIA antibodies in the absence of thrombocytopenia.