The professional definition of the family physician is not based on research that considers both patient and family physician perceptions. Questionnaire responses from 86 family physicians and 287 patients from ten family practices in Los Angeles were analyzed to compare their attitudes, perceptions, and expectations of the family physician. Both groups agreed the family physician could handle most medical problems (including hospital care), should provide continuity, should emphasize preventive medicine, and should be caring. The physician's manner and skill were felt equally important. Family physician and patient expectations conflicted in four major areas: referral, the handling of emotional problems, concern with and care of family, and the issue of autonomy. Such research may help the development of family practice and improve the patient-family physician relationship through improved graduate and continuing medical education for family physicians.