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Background Aspirin forms a cornerstone of management in patients with established cardiovascular disease (CVD). Despite proven efficacy, variability of aspirin response has long been recognised, with early studies suggesting rates of high on treatment platelet reactivity (HTPR) as ranging between 5 and 45%. Whether aspirin responsiveness relates to long-term prognosis in patients with CVD is unknown. Methods A prospective, single-centre analysis of 224 troponin positive non-ST elevation myocardial infarction (NSTEMI) patients undergoing coronary angiography. Aspirin-naive patients were loaded with 300 mg aspirin and maintained on 75 mg daily. Blood samples were obtained at the time of angiography and the VerifyNow Aspirin assay utilised to determine aspirin effect. The primary end point was all-cause mortality at 10 years. Results Time from aspirin loading (or admission on aspirin) to angiography was 4.9 ± 2.7 days. Platelet aggregation results, expressed as aspirin reaction units (ARU) were divided into tertiles: T1 (ARU 363–405) (n = 76), T2 (ARU 406–436) (n = 76), T3 (ARU 437–596) (n = 72). Higher ARU values were associated with increased mortality (log rank, p = 0.009), with those in the T3 having a 3-fold higher rate of events than those in the T1 (HR 3.03 [95% CI 1.33–6.99], p = 0.009) over a 10-year follow up. Conclusion Our study demonstrates that aspirin responsiveness is directly related to 10-year survival and may identify patients who may benefit from additional antithrombotic therapy. Further, ARU values less than the previously defined cut off 550 are associated with reduced survival at 10 years.