Objectives <p>Cryopreserved aortic allografts in pediatric patients have limited durability due to graft calcification, resulting in high rate of reoperations. Physiological hyperphosphatemia in the young, coupled with inflammatory responses against post-transplant allografts, accelerates allograft calcification in a rat model. We aimed to examine the anti-calcification effect of a phosphate binder, lanthanum carbonate, on aortic allografts in a growing porcine model with blood flow and pressure that resembled clinical settings.</p> Methods <p>Four-week-old male specific pathogen-free crossbred piglets were used as donors and recipients. The descending aortas harvested from 5 donors were divided, cryopreserved, and transplanted into the descending aorta of 10 recipient piglets. The lanthanum group received lanthanum carbonate (45&#xa0;mg/kg/day for 1 week preoperatively and 4 weeks postoperatively; <i>n</i> = 5) and was compared to the control group (without lanthanum carbonate; <i>n</i> = 5). The conduits were explanted at 8 weeks and examined using von Kossa staining and for calcium content quantification by atomic absorption spectroscopy. The sera and femurs were also retrieved to analyze adverse events of lanthanum carbonate.</p> Results <p>In the lanthanum group, allograft medial calcification developed less frequently, and the calcium content of the allografts was significantly lower than that in controls (<i>p</i> = 0.009). Body weight, hematocrit levels, and femur mineral density did not differ significantly between the groups at 8 weeks.</p> Conclusions <p>Our results suggest that short-term lanthanum carbonate administration may alleviate cryopreserved allograft calcification in young recipients, without adverse effects.</p>