Objective This study aimed to evaluate the efficacy of the Functional Independence Measure to assess preoperative frailty for elderly patients undergoing surgical aortic valve replacement. Methods Eighty-five patients >65 years who survived elective isolated aortic valve replacement from January 2008 to October 2015 were included. The mean age at the operation was 78 +/- 6 years old (n = 28 males, n = 57 females). The patients were divided into two groups according to their status at discharge: impossible to discharge home or hospitalization for >30 days (compromised group, n = 8), or unaffected (unaffected group, n = 77). Preoperative frailty was evaluated with the Functional Independence Measure, which comprises 18 items divided into six domains: self-care, sphincter control, mobility, locomotion, communication, and social cognition. Results The preoperative total Functional Independence Measure score was significantly lower in the compromised group (79 +/- 32) than in the unaffected group (120 +/- 9, p < 0.01). The preoperative motor Functional Independence Measure score was significantly lower in the compromised group (45 +/- 24) than in the unaffected group (85 +/- 9, p = < 0.01). The duration of postoperative intubation, intensive care unit stay, and postoperative hospitalization were significantly longer in the compromised group than in the unaffected group (48 +/- 67 vs 16 +/- 12 h, p < 0.01; 6.7 +/- 5.3 vs 3.4 +/- 2.0 days, p < 0.01; 34 +/- 27 vs 23 +/- 11 days, p = 0.02, respectively). Conclusions The preoperative Functional Independence Measure is effective for assessing preoperative frailty in elderly patients undergoing aortic valve replacement in terms of predicting operative morbidity.