A preexisting condition (or pre-existing condition) as it relates to health insurance is a diagnosed medical condition that exists at the time an individual applies for health insurance coverage. For instance, if a man suffered a heart attack in 1995, was diagnosed with heart disease, and prescribed the appropriate medication and then applied for insurance coverage in 2000, his coronary disease would be considered a preexisting condition.

Under Title I of the Health Insurance Portability and Accountability Act (HIPAA) passed by the United States Congress in 1996 to protect the health coverage of individuals and their families when the individual loses a job or changes jobs, group health insurance plans are limited in the restrictions that can be placed on insurance benefits payable for preexisting conditions. The plans may, however, refuse to pay benefits for such conditions for a period of one year to 18 months after enrollment in the plan. (That coverage may be reduced if the person in question had insurance coverage before enrollment in the plan.)

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