Continuity of care is an interaction between patient and doctor lasting over time. This relationship is governed by several factors related to the patient, to the doctor and to the health care system. This study evaluates some organizational aspects of the primary health care system of Norway which influence continuity of care. Factors such as practice organization, responsibilities for patients and availability of the physician are related to five conceptual aspects of continuity: the chronological, geographical, interdisciplinary, interpersonal and informational dimensions. In Norway patients are free to change primary care physicians as and when they wish. There is also a referral system and the patient cannot, in principle, go directly to a specialist or to a hospital. This open-access primary health care system provides a base from which continuity of care in other countries may be described and discussed.