Seventy atopic patients were studied. Pin-prick skin tests with cat epithelium extract (Ifidesa-Aríste-gui) were made. The results were compared by dividing the patients into a group with clinical manifestations of contact with cats and a group without clinical manifestations of contact with cats. Our results show that skin tests for cat epithelium, such as those carried out routinely in clinical practice, are not very sensitive or specific, and, therefore, are not suitable for diagnosis or prevalence studies.