Abstract: S-nitrosothiols exert a potent relaxant effect, mediated both by guanylate cyclase, and a cGMP-independent mechanism, upon non-vascular smooth muscle. Such types of smooth muscle include airway, gastrointestinal, bladder, uterine and corpus cavernosal. Thus, S-nitrosothiols may be used for the treatment or prevention of disorders associated with relation of smooth muscle, such as airway obstruction, and other respiratory disorders, bladder dysfunction, premature labor and impotence. Additionally, S-nitrosothiols may be used to alleviate smooth muscle contraction and spasm, and thus facilitate procedures involving diagnostic instrumentation, such as endoscopy, bronchoscopy, laparoscopy and cystoscopy. S-nitrosothiols also increase the binding affinity between hemoglobin and oxygen, and therefore, may be used to improve hemoglobin-oxygen binding, and oxygen transport to bodily tissues.