Communication between physicians and patients is an important domain of general practice, not as an objective in itself, but in order to diagnose and to manage patient care by exchanging information. An effective communication influences compliance and patient satisfaction positively, and patient's feelings of fear appear to be reduced. Quality improvement of medical professional emphasises objective assessment of their competence and actual performance in daily practice, since self-ratings have produced overestimations of service delivery. Therefore the question arises which assessment method(s) will have to be used. Direct observation of physician's performance is assumed to have the highest validity. But where and by whom should the observation be administered: in the daily practice or in a simulated surgery, by peer-observers, by regular patients or by standardized patients? Observation by trained and independent peers proved to be a valid and reliable method, but patients as consumers may attribute objective assessment substantially. Standardized patients may judge more competently than regular patients: they are independent form physician's care and they can compare different GPs in a standardized simulated setting. However, the question whether GP's performance in such a setting correlates with actual performance in the day-to-day practice, has not been answered yet. Therefore our study compares judgements of regular patients and standardized patients about communication performance of 100 GPs, in both daily practice setting and simulated surgery, with assessment of communication in both settings by peer-observers. Used methods, followed procedures, the study design and the results i.e. the predictive validity of patients' judgement for actual performance will be presented systematically.