Some health plans have experimented with increasing consumer cost sharing, on the theory that consumers will use less unnecessary health care if they are expected to bear some of the financial responsibility for it. However, it is unclear whether the resulting decrease in use is sustained beyond one or two years. In 2004 Mayo Clinic's self-funded health plan increased cost sharing for its employees and their dependents for specialty care visits (adding a $25 copayment to the high-premium option) and other services such as imaging, testing, and outpatient procedures (adding 10 or 20 percent coinsurance, depending on the option). The plan also removed all cost sharing for visits to primary care providers and for preventive services such as colorectal screening and mammography. The result was large decreases in the use of diagnostic testing and outpatient procedures that were sustained for four years, and an immediate decrease in the use of imaging that later rebounded (possibly to levels below the expected trend). Beneficiaries decreased visits to specialists but did not make greater use of primary care services. These results suggest that implementing relatively low levels of cost sharing can lead to a long-term decrease in utilization.