Abstract: Hydrogels releasing or producing NO, most preferably polymerizable biodegradable hydrogels capable of releasing physiological amounts of NO for prolonged periods of time, are applied to sites on or in a patient in need of treatment thereof for disorders such as restenosis, thrombosis, asthma, wound healing, arthritis, penile erectile dysfunction or other conditions where NO plays a significant role. The polymeric materials can be formed into films, coatings, or microparticles for application to medical devices, such as stents, vascular grafts and catheters. The polymeric materials can also be applied directly to biological tissues and can be polymerized in situ. The hydrogels are formed of macromers, which preferably include biodegradable regions, and have bound thereto groups that are released in situ to elevate or otherwise modulate NO levels at the site where treatment is needed.