Although health care professionals in The Netherlands are increasingly confronted with diverse immigrant groups, medical counselling and treatment of these groups has not been the subject of extensive research yet. From other studies it is well known that intercultural differences can have serious consequences for health care, e.g. in terms of risk of incorrect diagnoses or non-compliance. Eighty-seven autochthonous Dutch and immigrant (mainly from Turkey and Surinam) parents of child patients and their general practitioners (GPs) were recruited to investigate the influence of cultural differences on mutual understanding and patient compliance. Analyses of questionnaires and home interviews revealed that there is a relation between the cultural background of the patient and effectiveness of communication. Communication in consultations between GPs and persons from ethnic minorities is less effective than in consultations with Dutch persons: there is more misunderstanding, and also more non-compliance. In general, mutual understanding between GP and patient proves to be a strong predictor for patient compliance. These findings hold especially true for patients living in two worlds, i.e. a mixture of traditional and western cultures. The results are discussed in terms of methodological issues and practical implications for the health care providers.