Background Prosthesis-patient mismatch (PPM) has been shown to be related to worse survival and hemodynamic outcomes following valve replacement. Women with aortic stenosis (AS) have a smaller annulus than their male counterpart, making them more susceptible to PPM. The objective of this study was to compare the incidence of PPM in a female population with small aortic annulus (SAA) undergoing transcatheter aortic valve replacement (TAVR) versus surgical aortic valve replacement (SAVR) using the Carpentier Edwards Magna Ease bioprosthetic valves (19-21 mm) and the Edwards Sapien 3 and Sapien 3 Ultra transcatheter valves (20-23 mm). Methods This retrospective study was conducted using harmonized databases from two high-volume cardiac surgery centers. Female patients with SAA (≤23 mm) measured by echocardiography who underwent SAVR or TAVR between 2011 and 2022 were included. Patients with pure aortic regurgitation were excluded. The primary endpoint was to compare the incidence of moderate to severe PPM, both measured and predicted, in women receiving TAVR versus SAVR. Secondary endpoints included various clinical outcomes. Results A total of 426 women were included. 64.8% underwent SAVR (mean age: 75) and 35.2% underwent TAVR (mean age: 81). SAVR patients received 19- or 21-mm prostheses (32% and 68%, respectively). Almost all TAVR patients (94%) were assigned a 23 mm prosthesis, with the others receiving a 20 mm prosthesis. While 53% of SAVR patients were predicted to have a moderate to severe PPM (P-PPM), 39% of TAVR patients were predicted to do so ( P = .005). When it came to measured PPM (M-PPM), 73% of SAVR versus 32% of TAVR patients had moderate to severe PPM ( P < .001). Proportions were lower when adjusting for BMI > 30 (P-PPM - SAVR: 25%; TAVR: 19%; P = .148; M-PPM – SAVR: 64%; TAVR: 23%; P < .001). Conclusion In women with SAA, a larger proportion of SAVR patients had moderate to severe P-PPM or M-PPM compared to TAVR patients. Adjusting for BMI > 30 showed similar trends, although overall proportions were lower.