Legal Question in Real Estate Law in Illinois

You are not legally entitled to a written lease. If there is no written lease, you are operating under what would be called an oral month to month lease. If you do not pay your rent, the landlord would have the right to evict you.

I should add that the information in my previous answer does not apply to Chicago. Chicago has its own landlord tenant ordinance, and since I am not located near Chicago, I am not familiar with its ordinances.