OBJECTIVE As modifications are made to coils, monitoring the safety profile, ability to achieve high packing attenuation, and durability of occlusion as compared to the standard bare platinum coils is of paramount importance. We compared packing attenuation, initial occlusion, and recanalization rates between Cerecyte and bare platinum coils in the treatment of ruptured and unruptured cerebral aneurysms. METHODS We compared 63 patients (67 aneurysms) treated with Cerecyte coils with 65 patients (70 aneurysms) treated by using bare platinum coils. Results were classified by the Raymond score. Clinical outcomes were assessed by using a modified Rankin Scale. Angiographic and clinical follow-ups were performed routinely at 6 and 12 months after the intervention. RESULTS In the Cerecyte group, complete occlusion of the aneurysm (grade 1) was accomplished in 49% (33/67), a small residual neck (grade 2) was seen in 21% (14/67), and dome filling (grade 3) was seen in 30% (20/67). In the platinum group, 41% (29/70) were grade 1, 39% (27/70) were grade 2, and 20% (14/70) were grade 3 immediately postembolization. Mean packing attenuation was 43 +/- 28% in the Cerecyte group and 40 +/- 23% in the bare platinum group (P = .68). Twelve-month follow-up data were available for 54% (36/67) of the Cerecyte population and 43% (30/70) of the bare platinum population. There were 5 cases of neck recanalization (11%) in the Cerecyte group and 11 cases (23%) in the bare platinum group (P = .17). No rebleeds were noted in the follow-up period. CONCLUSIONS Cerecyte coils have a satisfactory safety profile. We were able to achieve high packing attenuations and initial occlusion rates similar to those obtainable with platinum coils.