Background: Compared with other manifestations of cardiovascular disease, peripheral arterial disease (PAD)is under-diagnosed. This study aims to investigate the prevalence, risk profile and cardiovascular outcomes of undiagnosed PAD in Australian general practices. Method: A sub-study of the Australian Reduction of Atherothrombosis for Continued Health (REACH)Registry, a prospective cohort study of patients at high risk of atherothrombosis recruited from Australian general practices. Eligible patients for this study had no previous clinical diagnosis of PAD and had an ankle-brachial index (ABI)≤1.4 at recruitment. Results: Peripheral arterial disease was undiagnosed in 34% Australian REACH participants, 28% patients had low ABI (ABI < 0.9)and 11% had intermittent claudication (IC)based on responses to the Edinburgh Claudication Questionnaire (ECQ). We found no significant differences in risk factor control between patient with or without PAD. Intermittent claudication patients had higher risks of non-fatal cardiovascular events and PAD interventions at one year, whereas all-cause mortality rate was higher among patients with ABI<0.9, especially in those who also reported IC. Finally, an ABI < 0.9, together with poorly controlled risk factors were independent predictors of incident IC at one year. Conclusions: This study suggests a high rate of undiagnosed PAD among high risk patients in Australian primary health care. These patients are at high risk of events and therefore would potentially benefit from better secondary prevention measures.