The purpose of this study is to investigate the efficacy and safety of a topical gel formulation of nitroglycerin, in comparison to a matching placebo, for patients with moderate to severe primary Raynaud's phenomenon or patients with Raynaud's phenomenon secondary to autoimmune diseases, such as scleroderma.

Inclusion Criteria:

• Clinical diagnosis of Raynaud's phenomenon
• 2 or more Raynaud's events on a typical winter day
• Agree to discontinue current treatments for Raynaud's
• Negative pregnancy test and agree to use effective contraception during study

Exclusion Criteria:

• Current use of nitrate medications or medications known to interact with nitroglycerin
• Patients who currently use medications, like calcium channel blockers, that might interfere with study medication
• Patients with a known allergy to nitroglycerin or common topical ingredients
• Patients with a history of migraine headaches
• Patients with a history of unstable medical problems
• Patients with cognitive or language difficulties that would impair completion of assessment instruments
• Patients with lab screening values more than 20% outside normal range
• Patients with non-epithelialized skin lesions, in the area where the gel is to be applied, at the time of screening
• Pregnant or nursing women
• Women of child-bearing potential who are unwilling to comply with the contraceptive requirements