A growing percentage of Medicaid patients are receiving medical care within a managed care system. This policy change has raised concerns about whether safety-net providers can maintain their share of Medi-Cal (California Medicaid) patients. From 1995 to 1997 several of California's counties implemented mandatory Medi-Cal managed care. The majority of California's safety-net primary care clinics experienced a decline in the percentage of their patients insured by Medi-Cal. However, after the overall decline in the number of Medi-Cal beneficiaries was controlled for, the increased penetration of Medi-Cal managed care in a county was not independently associated with a decline in clinics' share of Medi-Cal patients. Despite this fact, it may become increasingly difficult for clinics to maintain their current level of services with declining Medi-Cal enrollment and other anticipated reforms in their funding.