Background: Despite meticulous hemostasis, persistent postoperative drain output following posterior cervical spine procedures often necessitates a prolonged length of hospital stay. We sought to determine if thrombin-soaked absorbable gelatin compressed sponge can decrease postoperative drain output and the length of hospital stay after multilevel posterior cervical spine surgery. Methods: We performed a retrospective analysis of forty-three pairs of patients who had undergone either posterior cervical decompression and/or fusion of three or more levels by the same surgeon. The patients were matched according to intraoperative blood loss, age, sex, and number of involved levels. Control patients were managed between 2004 and 2007, whereas study patients were managed between 2008 and 2011. The only variable between the study and control groups was that, in the study group, absorbable gelatin compressed sponge was soaked in thrombin and applied over the exposed spine before wound closure. A subfascial drain was used in all patients. Total drain output, time for the drainage to decrease to <30 mL per eight-hour shift (at which point the drain was discontinued), the length of stay, the number of readmissions, and postoperative complications were analyzed. Results: Total drain output averaged 93 mL in the study group and 204 mL in the control group (p < 0.0001). The average time for the drainage to decrease to <30 mL per eight-hour shift was 2.5 shifts in the study group and 4.4 shifts in the control group (p < 0.0001). Length of stay averaged 1.3 days (cumulative total, fifty-seven days) in the study group and 2.2 days (cumulative total, ninety-five days) in the control group (p < 0.0001). Persistent drain output was the primary reason preventing discharge on the first postoperative day. There were no infections, epidural hematomas, or readmissions within thirty days of discharge in either group. No patient developed adverse reactions attributable to the thrombin-soaked absorbable gelatin compressed sponge. Conclusions: Application of thrombin-soaked absorbable gelatin compressed sponge at the end of multilevel posterior cervical spinal surgery significantly decreased postoperative drain output and consequent hospital stay. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.