Porphyria cutanea tarda (PCT) is an iron-related disorder that responds to treatment by phlebotomy or low-dose hydroxychloroquine, but comparative data on these treatments are limited. The hypothesis is that hydroxychloroquine is noninferior to phlebotomy in terms of time to remission. Patients with well documented PCT are assigned to treatment by randomization if specific criteria are met. All patients are followed until remission - defined as achieving a normal plasma porphyrin concentration.