Cardiac troponin I is a sensitive marker of myonecrosis. Data regarding the prognostic value of troponin I increase after percutaneous coronary intervention (PCI) are conflicting. A recent American College of Cardiology/American Heart Association statement defined a troponin I increase >3 times the 99th percentile as periprocedural myocardial infarction (MI). We sought to evaluate whether or not, in patients with a successful elective PCI judged on angiographic and clinical criteria, the postprocedural increase of troponin I could predict 1-year outcomes. A cohort of 3,200 consecutive patients with successful elective PCI was studied. End points included death/MI and major adverse cardiac events at 1 year. A troponin I increase >97.5th percentile was observed in 1,402 patients (43.8%, mean 0.32 ng/ml, range 0.01 to 4.94). A total of 751 patients (23.4%) had a troponin I increase >3 x 99th percentile. Troponin I status was associated with more complex coronary disease (19.6% vs 16.4%, p <0.005) and multivessel PCI (2.1 vs 1.6, p <0.001). At 1 year, there was no difference in death/MI (2.8% vs 3.5%, p = 0.3) or in major adverse cardiac events (9.6% vs 10.4%, p = 0.5) according to the level of troponin I increase. The lack of association between troponin I increase after PCI and outcome was found when troponin I increase was used as a continuous or a categorical variable. Logistic regression models failed to find any threshold from which troponin I increase could affect outcome. In conclusion, a small troponin I increase after a successful elective PCI was not infrequent and did not affect outcome in our study. The definition of periprocedural MI may be too strict. Measurement of troponin I after a successful PCI is questionable.