In a semi-replication study, 103 videotaped real-life general practice consultations of patients with hypertension were observed with Roter's interaction Analysis System (RIAS). RIAS consists of a detailed category system meant to measure each verbal utterance of physician and patient (distinguished in taskrelated behavior and socio-emotional behavior) and a set of global affect-ratings. In this article, only general practitioner (GF) behavior is studied. GP's behavior is related to panel-assessed quality of care on three separate dimensions (technical-medical, psychosocial, and the management of the physicianpatient relationship). A remarkably high percentage of the variance in the quality assessments (ranging from 59% to 70%) was explained by RIAS. The global affect-ratings proved to have the strongest influence in all quality assessments. In addition, task-related behavior seems to be more important in medical technical behavior, whereas socio-emotional behavior, and especially the psycho- In medical communication two types of behavior are thought to be important: instrumental behavior and affective behavior. 1 " 11 They correspond with the two main purposes the doctor has in the medical consultation: information exchange, which is necessary for solving the medical problem; 7 ' 12 " 22 and creating a therapeutic relationship, which is necessary for managing the psychosocial aspects of patient's health problems and gaining patient's confidence. 2 types of behavior are both so important in medical practice is that patients, when seeing a doctor, have two different types of needs that have to be met. 32 " 34 As Engel 32 stated, these are "the need to know and understand" (to know what is the matter with him or her, what causes the pain, and how this can be stilled) and the "the need to feel known and understood" (to know that he or she is accepted by the doctor as a person and is not seen as a malingerer). While most people agree about the relevance of both types of behavior, there is considerable debate about the relative importance of both. 34 Researchers from a psychotherapeutic background (with Rogers 35 and Balint 23 as leading theorists) claim the predominance of affective behavior, 2 · 5 -36 while others (mostly inspired by Bales' observation system, which is based on problem solving theories 37 ), claim that instrumental behavior is 283