In patients suffering from atopic dermatitis (AD), we often find intolerance reactions against wool, whereas irritation by synthetic fibers is still a matter of discussion. In a randomized clinical study on 55 patients with AD and 31 healthy controls, we investigated the irritative capacity of poncho-like shirts made of 4 different materials (A: cotton; B, C, D: synthetics of different fiber structure). The intensity of itching or discomfort due to repeated wearing of these shirts was evaluated by means of a point system (max.comfort = 10 points, max. discomfort = 1 point). Our study clearly showed that the irritative capacity of synthetic shirts is significantly higher in patients with AD, while cotton shirts were best tolerated. We also observed significant difference regarding the surface structure and diameter of the synthetic fibers under investigation.