Floseal is a novel matrix hemostatic sealant composed of collagen-derived particles and topical bovine-derived thrombin. It is applied as a high-viscosity gel for hemostasis and has been clinically proven to control bleeding. This study is a prospective, randomized, controlled clinical trial of Floseal sealant compared to traditional suction cautery hemostasis in children undergoing adenoidectomy. Seventy patients (mean age 7.0 yrs, 45.7% male) with obstructive sleep apnea underwent traditional cold steel adenoidectomy with an adenoid curette and were then randomized to receive the hemostatic sealant (Floseal) or cautery to obtain hemostasis. Patients were crossed over to the other hemostatic technique if hemostasis was not achieved after more than 100 mL of blood loss or 15 minutes elapsed time. Objective data collected included time to hemostasis and blood loss during hemostasis. Visual analog scales (VAS) were used to record subjective data by the operating surgeon including bleeding following adenoid pack removal (0 = none, 3 = brisk) and ease of operation (1 = extremely easy, 6 = extremely difficult). Parents recorded diet on a journal and were contacted by phone at postoperative day 7 and questioned with regard to return to regular diet and use of narcotics. Compared to patients in the cautery group (n = 35), Floseal patients (n = 35) had significantly shorter times to hemostasis (0.6 +/- 1.3 minutes vs 9.5 +/- 5.4 minutes [mean +/- SD], P < 0.001), less blood loss (2.5 +/- 9.2 mL vs 29.4 +/- 27.1 mL, P < 0.001), less subjective bleeding (0.0 +/- 0.6 vs 2.0 +/- 0.7, [median 4-point VAS +/- SD], P < 0.001), and subjectively easier operations (2.6 +/- 1.0 vs 5.2 +/- 1.0 [mean 6-point VAS +/- SD], P < 0.001). Furthermore, Floseal patients returned to regular diet earlier (2.7 +/- 0.7 vs 4.1 +/- 0.5 days [mean +/- SD], P < 0.001) and had less use of narcotics at 7 days postoperatively (40% vs 69%, P < 0.05). Lastly, three patients in the cautery group were crossed over to the Floseal group, but no Floseal subjects were crossed over to the cautery group. The retail cost of Floseal is US 85 dollars. Operating room costs are estimated at US 12 dollars/minute. Reducing the operative length by 8.9 minutes on average produces a cost savings of US 106.80 dollars per operation. There were no complications in either experimental group including postoperative hemorrhage, hospitalization, blood transfusion, or aspiration. Floseal matrix hemostatic sealant is a safe, efficacious, easy, and cost-effective technique for obtaining hemostasis in children undergoing adenoidectomy. Limitations of the study include the fact that it is nonblinded, which does allow for some bias in the subjective data recorded. However, utilizing 4 different operating surgeons, 3 of whom were not affiliated with the study, minimized this. CLINICAL SIGNIFICANCE OF STUDY: This study demonstrates the safety and efficacy of a novel hemostatic sealant in children undergoing adenoidectomy. Floseal matrix hemostatic sealant can be used as a first-line hemostatic agent, and it is a good tool in the armamentarium of otolaryngologists who encounter significant bleeding following adenoidectomy.