A prospective, randomized trial was designed to compare the standard Kenalog injection of established hypertrophic sternal scars with topical silicone gel sheets (Spenco). Fourteen poststernotomy cardiac patients with symptomatic scars were randomized to treatment in one-half of the scar with Kenalog injection. Simultaneously, the other half of the scar received the silicone gel sheet. The standard Kenalog injection used was 40 mg/ml x 1 cc, mixed with 1 cc of 1% Xylocaine with epinephrine. The gel sheets were worn continuously for 12 hours for 12 weeks. Pretreatment and posttreatment photographs were compared for color and appearance by blindfolded observers. Scar measurements (length, width, and height) were taken weekly in each area, and the patients were asked to rank their symptoms within each half as worse, the same, or better. The primary outcome of patient preference was analyzed sequentially, and the recruitment was terminated after 11 patients had completed the study, 10 of whom favored the silicone gel treatment (p < 0.05). Three patients remained in the treatment phase at the time of termination and completed the study subsequently. For the total sample of 14 subjects, 11 preferred the silicone gel, 1 expressed no preference, and 2 preferred the injection. The average time to improvement was 3.9 +/- 0.62 days (gel) versus 6.8 +/- 1.86 days (Kenalog). This study demonstrates that silicone gel sheets provide earlier symptomatic relief and a more aesthetic scar and are the preferred treatment of patients with symptomatic hypertrophic sternal scars.