Critical illness insurance, otherwise known as critical illness cover or a dread disease policy, is an insurance product in which the insurer is contracted to typically make a lump sum cash payment if the policyholder is diagnosed with one of the specific illnesses on a predetermined list as part of an insurance policy.

The policy may also be structured to pay out regular income and the payout may also be on the policyholder undergoing a surgical procedure, for example, having a heart bypass operation.

The policy may require the policyholder to survive a minimum number of days (the survival period) from when the illness was first diagnosed. The survival period used varies from company to company, however, 14 days is the most typical survival period used.

The contract terms contain specific rules that define when a diagnosis of a critical illness is considered valid. It may state that the diagnosis need be made by a physician who specializes in that illness or condition, or it may name specific tests, e.g. EKG changes of a myocardial infarction, that confirm the diagnosis.