 A recent randomized controlled trial of aneurysm coiling revealed that aneurysms between 2 and 9.9 mm diameter were more likely to have an improved angiographic and composite clinical outcome when treated with hydrogel-coated coils, an improvement inferred to result from higher packing density afforded by hydrogel expansion1. The use of hydrogel coils is associated with technical difficulties related to expansion and limited time for deployment. The investigators theorize that similar results could be achieved by using more voluminous bare platinum coils, leading to improved packing density compared to smaller caliber coils, and thus result in lower incidence of remnants or residuals. The relationship between packing densities and composite clinical endpoints having never been shown in a robust fashion, the investigators therefore propose a randomized clinical trial opposing coiling with soft 15-caliber coils to 10-caliber bare platinum coils in aneurysms varying in size from 3 to 9.9 mm. 