Rapid innovation in vital bleaching has increased the popularity of tooth whitening among dental professionals and patients. A broad range of peroxide-based treatments are currently available including those that are professionally-administered (in-office), professionally-dispensed (custom-tray-based systems), and self-directed (over-the-counter). Recently, a novel, flexible polyethylene bleaching strip was introduced that delivers a hydrogen peroxide bleaching gel to the anterior dentition. This "trayless" system, available in professional-strength and over-the-counter versions, reportedly offers advantages with respect to overall peroxide dose, contact time, and ease-of-use compared to other delivery systems. This paper reviews the relevant published clinical research on whitening strips tested among a broad range of patients commonly encountered in contemporary dental practices.