The effect of managed care on important attributes of primary care is poorly understood. Of particular concern is the potential for annual bidding on managed care contracts, which may cause forced discontinuity of care. We examined the effect of insurance type and insurance-mandated disruption in continuity of care on the quality of primary care. A cross-sectional study design was used to examine 1839 patient visits to 138 community-based primary care physicians. The quality of primary care delivery was measured with the Components of Primary Care Instrument, a patient-reported indicator of physician knowledge of the patient, interpersonal communication, coordination of care, continuity of care, and patients' preference to see their regular physician. No significant differences in any of the five indicators of primary care quality were found between patients with independent provider association/preferred provider organization (IPA/PPO) and fee-for-service insurance. Patients with IPA/PPO health insurance were four times as likely as patients with fee-for-service insurance to report a forced change in their primary care physician (P < or = .01). Individuals forced to change their physician because of changes in their health care insurance scored significantly lower on all five indicators of primary care quality (P < or = .01). The quality of primary care appears to be less dependent on the payment system than on the maintenance of the patient-physician relationship. Forced disruption of continuity of care is detrimental to patient receipt of quality primary care, and is a potential negative consequence of annual bidding for managed care contracts.