Carbon monoxide is an intrinsic signaling molecule with importance on par with that of nitric oxide. During the past decade, pharmacological studies have amply demonstrated the therapeutic potential of carbon monoxide. However, such studies were mostly based on CO inhalation and metal-based CO releasing molecules (CO-RMs). The field is now at the stage that a major effort is needed to develop pharmaceutically acceptable forms of CO for delivery via various routes such as oral, injection, infusion, or topical applications. This review examines the state of the art, discusses existing hurdles to overcome, and proposes developmental strategies necessary to address remaining drug delivery issues.