The study was performed in 6 Thai children with primary acquired cold urticaria. They all suffered from generalized urticaria and two of them also had angioedema. All of them had normal erythrocyte sedimentation rate, complement 3 and negative VDRL, TPHA, hepatitis B screen and cold agglutinin titer. Cryoglobulin was checked in 3 cases and showed negative results A double-blind cross-over study to compare the effectiveness of cyproheptadine and ketotifen demonstrated that the efficacy of cyproheptadine and ketotifen on clinical symptoms and ice cube test was not significantly different (p > 0.05). Both of them showed good results in the treatment of cold urticaria with mild side effects. During the follow up, 5 cases showed complete recovery while the other one developed one or two exacerbations per year upon cold exposure. However, the symptoms were mild and subsided on administration of one or two doses of H1 antihistamine. Our data demonstrated that ketotifen was as effective as cyproheptadine in the treatment of cold urticaria in Thai children.