Many people prefer an HMO health insurance plan because it has small co-pays and out-of-pocket epenses. The in-network providers of HMO health insurance are relatively small in number than with other health insurance organizations. You can see the same physician or health care provider for as long as your plan allows you to. You can be sure that you are well-taken care of by maintaining a good relationship with your doctor. Because of the small number of doctors or health care providers in an HMO, the organization can monitor the kind of service they provide the insured and if they are complying with the guidelines. With an HMO, you have to see a primary care physician first who can advise you if you need to see other health care provider or specialist. However, there are some health insurance companies that offer an [Open Access HMOs health plan. With Open Access HMO health plans, there is no need for a referral before consulting another specialist. However, with open access, the co-pay and coinsurance may be higher than the one where you need a referral first. Some HMO health care plans offer preventive care for low copayment or sometimes for free. The objective is to help policyholders manage their health care needs. It will also help these plan holders detect any developing diseases with regular visits to doctors as indicated in their plans. Answer by Rosie Yeh -- June 19.2009 @3:09 pm