Warping of costal cartilage is well described; however, its strength and abundance still make it a desirable graft material, especially in complex reconstructive rhinoplasty. Despite multiple methods of cartilage harvest, carving, and preimplantation treatment being developed over the years, warp remains a challenging clinical problem. OBJECTIVE To assess whether the 30°oblique split method of preparing costal cartilage grafts produces less warping of the graft than the current standard of harvesting the central segment of a rib using the concentric carving method. DESIGN, SETTING, AND PARTICIPANTS This in vitro cadaveric study evaluated the warping of costal cartilage grafts using the oblique split method with an angle of 30°or the concentric carving method during a 3-month period beginning in December 2014. MAIN OUTCOMES AND MEASURES Millimeters of warp from baseline (at 1 hour) and at 1, 2, and 3 months, measured in the frontal and lateral planes. RESULTS Among 74 costal cartilage grafts (using the oblique split method with an angle of 30°in 41 and the concentric carving method in 33), the mean amount of warp in the frontal plane was between 1.12 mm (95% CI, 0.96-1.28 mm) and 1.57 mm (95% CI, 0.94-2.20 mm) for the oblique group and between 1.18 mm (95% CI, 0.98-1.38 mm) and 1.29 mm (95% CI, 0.86-1.72 mm) for the concentric group during the 3-month period. There was no statistically significant difference in the frontal plane between the 2 methods at 1 hour (P = .45; 0.10 mm, 95% CI, −0.38 to 0.17 mm), 1 month (P = .32; 0.13 mm, 95% CI, −0.13 to 0.40 mm), 2 months (P = .50; 0.28 mm, 95% CI, −0.55 to 1.11 mm), or 3 months (P = .15; 0.22 mm, 95% CI, −0.08 to 0.52 mm) using the t test, regression analysis, or panel data analysis. Similarly, no significant difference was found in the lateral plane at 1 hour (P = .89; 0.04 mm, 95% CI, −0.49 to 0.56 mm), 1 month (P = .82; 0.07 mm, 95% CI, −0.56 to 0.70 mm), 2 months (P = .29; 0.40 mm, 95% CI, −0.36 to 1.17 mm), or 3 months (P = .63; 0.22 mm, 95% CI, −0.70 to 1.13 mm) using the t test. Two grafts were excluded due to desiccation. CONCLUSIONS AND RELEVANCE The 30°oblique split and concentric carving methods of costal cartilage graft carving are equivalent in terms of the amount of warp. The oblique split method may be superior because of easier carving and the increased volume of material. LEVEL OF EVIDENCE NA.