The effects of topical glyceryl trinitrate in Raynaud's disease were compared with those of placebo in a double-blind, crossover trial in 17 patients with bilateral Raynaud's disease and an associated collagen disease, who were receiving oral sympatholytic agents at the maximum levels they could tolerate. 1% glyceryl trinitrate ointment or a placebo of lanolin was applied to one hand only for 6 weeks, then patients changed to the other preparation for 6 weeks. The results were evaluated every 2 weeks. The frequency of attacks, severity of attacks, and size of ulcers in the treated hand were significantly lower when the patients were using glyceryl trinitrate ointment than when they were using placebo. The treatment of Raynaud's disease may be improved by using topical glyceryl trinitrate ointment as an adjunct to a basic regimen of oral sympatholytic agents. Glyceryl trinitrate ointment may obviate the need for more aggressive treatment, such as intraarterial reserpine, in selected patients.