Pre-existing conditions are medical ailments for which you have already received or are receiving treatment for. Pregnancy, AIDS, high-blood pressure and stroke are all forms of pre-existing conditions. Different insurance carriers have their own policies for pre-existing conditions. Some insurance providers offer coverage after a certain waiting period while others totally exclude certain conditions. Having a pre-existing condition obviously puts you at a higher risk for compensation than people without pre-existing conditions and is therefore more difficult to get insurance cover.