Objectives: This investigation explored the short-term prognostic value of pentraxin-3 (PTX3) levels in patients with non-ST-segment elevation myocardial infarction (NSTEMI) treated by percutaneous coronary intervention (PCI). Methods: We measured plasma levels of PTX3 and other biomarkers in 525 PCI-treated NSTEMI patients (mean age, 57.7 years; 328 males). The associations of PTX3 levels with cardiac events and cardiac deaths occurring within 30 days of discharge were evaluated with multivariable Cox proportional hazard models. Results: Renal function, diabetes prevalence, systolic blood pressure, heart rate and ejection fraction differed significantly in the high PTX3 (≥3.0 ng/ml, n = 107) and low PTX3 (<3.0 ng/ml, n = 418) groups (all p < 0.05). Plasma PTX3 levels were correlated with high-sensitivity C-reactive protein, troponin T and N-terminal pro-B-type natriuretic peptide in NSTEMI patients (all p < 0.05). Kaplan-Meier analysis showed in-hospital and 30-day cardiac events and deaths were higher in the high PTX3 group (both p < 0.01). Elevated PTX3 was an independent predictor of 30-day cardiac events (95% CI 1.09-1.68; p = 0.006) and mortality (95% CI 1.18-2.15; p = 0.002). Conclusions: An elevated plasma level of PTX3 predicts 30-day cardiac events and mortality in PCI-treated NSTEMI patients.