Numerous studies have linked prosthesispatient mismatch (PPM) after aortic valve replacement (AVR) to adverse outcomes. Its correlation with long-term survival has been described but with contradicting results. This systematic review and meta-analysis of observational studies aims to determine the hazard of PPM after AVR. The Medline and EMBase databases were searched for English-language original publications. Two researchers independently screened studies and extracted data. Pooled estimates were obtained by random effects model. Subgroup analyses were performed to detect sources of heterogeneity. The search yielded 348 potentially relevant studies; 34 were included comprising 27 186 patients and 133 141 patient-years. Defined by the universally accredited indexed effective orifice area 0.85 cm(2)/m(2), 44.2 of Prosthesispatient mismatch is associated with an increase in all-cause and cardiac-related mortality over long-term follow-up. We recommend that current efforts to prevent PPM should receive more emphasis and a widespread acceptance to improve long-term survival after AVR.