Now THAT could make a difference. In general, group policies are priced for the whole group with the assumption of some bad apples (which is why you pay a higher premium than you might think you deserve to pay as an otherwise "healthy" person.) In a small company, however, underwriting will be much easier and more detailed, and the chances of being denied covereage due to a serious pre-existing condition would be quite a bit higher than if you were just one of many thousand employees to blend into a larger group policy.