Background: Exhibiting potential causes of chronic urticaria in routine daily practice is a complex procedure. A guideline, developed by the researchers, investigating the etiology of chronic urticaria was evaluated in this study. In this guideline erythrocyte sedimentation rate, complete blood count, urine analysis and direct microscopic examination of stool for parasites were routine and other diagnostic procedures were requested according to clinical findings of potential causes. Objective: The purpose of the study was to determine the rate of implementation of the guideline considering a daily practice. Material and Methods: Following diagnosis of chronic urticaria, patients were interrogated with a standard questionnaire form, and were examined in order to determine the clinical findings of possible causes of the disease. The records of 903 patients in total were retrospectively evaluated. During the evaluation process, the necessary and unnecessary diagnostic procedures regarding the guideline were determined by using computerized algorithms. During evaluation some parameters such as age and gender of patients, duration and severity of the disease, and numbers and types of diagnostic procedures affecting the grade of the request and completion were also taken into account. Results: The total number of necessary procedures was 4070, less than one third of which were requested by the physicians. However, the patients completed more than three fourths of the requested procedures. Moreover, the physicians requested some unnecessary procedures in almost one third of the patients. Conclusion: According to clinical findings, lower threshold for necessity of investigation leads to more failure in implementation of a guideline. Guidelines developed for the etiological diagnosis of chronic urticaria should be evaluated retrospectively on data from daily practices to evaluate the utility of a guideline.