BACKGROUND: Zinc (Zn) has been reported to play an important role in wound healing (WH). Nevertheless, the effect of Zn in chronic limb-threatening ischemia (CLTI) patients is unclear. This study investigated the effect of Zn on the clinical outcomes of CLTI patients undergoing bypass surgery.Methods and Results:This study reviewed 111 consecutive patients who underwent an infrainguinal bypass from 2012 to 2020. Patients with Zn deficiency (serum Zn level <60 μg/dL) received oral Zn supplementation and maintained a normal level until WH. This study aimed to explore: (1) the effect of Zn deficiency; and (2) Zn supplementation in Zn-deficient patients on the clinical outcomes of this cohort. Patients with Zn deficiency, Zn supplementation, and no Zn supplementation despite Zn deficiency accounted for 48, 21, and 42 patients, respectively. (1) Zn deficiency was associated with WH (HR, 0.47; 95% CI, 0.29-0.78: P=0.003), major adverse limb events (MALE) (HR, 2.53; 95% CI, 1.26-5.09: P=0.009), and major amputation or death (HR, 3.17; 95% CI, 1.51-6.63: P=0.002). (2) Zn supplementation was positively related to WH (HR, 2.30; 95% CI, 1.21-4.34: P=0.011). This result was confirmed using propensity score matching (HR, 2.24; 95% CI, 1.02-4.87: P=0.043). CONCLUSIONS: The current study revealed that Zn level was associated with clinical outcomes in CLTI patients after bypass surgery. Oral Zn supplementation could improve WH in these patients.