Acquired cold urticaria is an infrequent physical urticaria that can provoke severe systemic reactions. Histamine is the primary mediator, but leukotrienes are also involved in the pathogenesis. H(1) antihistamines are recommended as first-choice treatment, but their efficacy is sometimes unsatisfactory. On the basis of pathogenic knowledge, it can be hypothesized that a combination therapy with antihistamines and leukotriene receptor antagonists is more effective than each drug given alone. We tested this hypothesis in 2 patients with severe systemic cold urticaria poorly responsive to conventional therapy. The patients underwent 3 consecutive treatment regimens (each of 2 weeks): cetirizine (10 mg once a day); zafirlukast (20 mg twice a day); and their combination. They were clinically evaluated, after each regimen, by means of a visual analog scale and ice-cube test. The combination therapy was superior to the 2 drugs given alone, as testified by subjective and objective evaluations.