Background Autologous saphenous vein is the preferred conduit for below-the-knee bypasses in patients with critical limb-threatening ischemia. Alternative graft must be considered for patients without (autologous saphenous vein). The aim of this article is to evaluate the mid-term performance of arterial allograft (AA) and venous allograft (VA) used as alternative conduits. Methods This retrospective study included patients with critical limb-threatening ischemia, with or without a history of homolateral femoropopliteal bypass, and no autologous veins were available who underwent infrainguinal arterial reconstructions using VA or AA from 2008 to 2018. Patients undergoing revision operations for infected bypasses were excluded. Primary patency (PP), primary assisted patency, secondary patency, major amputation, and death from any cause were the endpoints. For each event, a set of analyses were performed. Results Overall, 111 patients (63 VAs and 48 AAs) were included, with 108 having below-the-knee bypass. The median follow-up time was 27.8 months (15.6–37.4). The difference in PP between the 2 allograft types was significant (P = 0.049), with 65.9% (43.7–81.0), 44.1% (24.2–62.3), and 44.1% (24.2–62.3) in the AA group, respectively, at 6, 12, and 18 months, whereas 55.6% (40.0–68.6), 46.0% (30.6–60.2), and 33.2% (18.2–49.0) in the VA group. The choice of an AA over a VA was an independent factor associated with patency (for PP: hazard ratio [HR] = 0.43 [0.24–0.75], P = 0.003); primary assisted patency: HR = 0.52 (0.30–0.89], P = 0.018; and secondary patency: HR = 0.49 (0.27–0.88), P = 0.016. The allograft type did not affect either the incidence of major amputation or death from any cause (respectively, HR = 1.20 [0.49–2.93], and 0.88 [0.37–2.14]). Conclusions The nature of the allograft appears to influence the patency of infrainguinal reconstruction, but not the course of the disease. Performant alternative grafts answering infectious issues are needed.