OBJECTIVE To identify claudicants at high risk (and low risk) of late vascular morbidity and mortality after peripheral bypass surgery. METHODS Prospective cohort study with mean follow-up of 8.6 years. METHODS One-hundred and fifty-five claudicants selected for peripheral bypass surgery. Only three patients were lost to follow-up. End points were major vascular events, additional interventions, all-cause mortality, and functional outcome. RESULTS Major vascular events occurred in 59 patients. Life-table analysis revealed an annual risk increase of 3.5%. Strong predictors were hypertension (hazard ratio (HR) 2.7; 95% confidence interval (CI) 1.5-4.8), diabetes (HR 2.4; 95% CI 1.0-5.4) and cardiac disease (HR 2.2; 95% CI 1.2-4.0). Sixty patients needed additional interventions with a highest incidence (17%) in the first year, and thereafter 2.8% each year. None of the known risk factors were associated with an altered incidence of interventions. Approximately 3.5% of patients died per year compared with 2% per year in the control group. Prominent high-risk factors for mortality were cardiac disease (HR 3.3; 95% CI 1.8-6.0) and diabetes (HR 3.0; 95% CI 1.5-7.1). CONCLUSIONS Major vascular events and additional interventions are common and serious in claudicants. However, it is possible to select low-risk patients in which peripheral bypass surgery is justified.