To determine gutter size and stent-graft geometry in an in vitro juxtarenal aneurysm model using various chimney graft (CG) configurations. Two silicone juxtarenal aortic aneurysm models were constructed combining different diameters of the aorta and renal artery. In a single-branched CG configuration, 2 sizes (23 and 28.5 mm) of Excluder stent-grafts were tested individually with 2 sizes of 2 types of CGs: Advanta balloon-expandable (BE) stent-grafts (6×59 and 12×61 mm) and Viabahn self-expanding (SE) stent-grafts (6×50 and 13×50 mm). All combinations were tested with a short (10-mm) and long (20-mm) sealing zone between the CG and main graft (total 16 configurations). Immediately after deployment, the CG configuration was scanned using a 64-slice computed tomography scanner. Gutter sizes were measured at different levels of the sealing zone. At the top of the sealing zone, the gutters were significantly larger in the BE CGs compared to SE CGs in combination with the 23-mm main graft (p=0.021). At the bottom of the sealing zone, there were no statistically significant differences (p=0.77). No significant differences were seen using the 28.5-mm main graft. Median gutter size was larger in the 6-mm CGs. The length of the sealing zone had no influence on gutter size. Significant compression of the main graft was found using 12 or 13-mm CGs compared to 6-mm CGs (p=0.001). In this in vitro study, the CG configurations with BE stent-grafts show larger gutters than configurations with SE stent-grafts in small main grafts. Main graft compression is increased using wider CG stent-grafts.