Plastic surgeons frequently administer botulinum toxin A (Botox) or collagen as monotherapy to treat glabellar furrows. This study evaluates the possible advantages of combination therapy. Sixty-five patients with moderate to severe glabellar rhytids were prospectively randomized to receive standard injections of Botox, Zyderm II collagen, or a combination. Improvement in rhytids was assessed over 3 months using patient satisfaction scores and an independent physician evaluation. Baseline wrinkle severity was similar in all 3 groups. By 1 month posttreatment, the combination arm showed significantly greater improvement in furrows (79% compared with only 56% and 50% in the Botox and Zyderm arms, respectively; P < 0.05). At 3 months postinjection, the dual-therapy arm maintained better improvement (57% versus 33% and 27% in the monotherapy arms; P < 0.05). Patient satisfaction further highlighted the superiority of the combination approach. By simultaneously addressing the static and dynamic aspects of glabellar furrows, dual therapy provides optimal treatment of this problem.