I received a ticket for expired vehicle registration. Can I get it dismissed in court?

In CA if you bring proof of registration (shortly after being cited) when you go to court the case is usually dismissed with a $25 administration fee. I would think that this would apply in IL. Check with clerk or traffic ticket attorney.

It would be up to the judge, but in Cook county, 99% of these tickets are dismissed.

In most (if not all) courthouses in Cook County - when you bring in proof of renewed registration for the vehicle that was driven at the time of the ticket issuance, that ticket will routinely be dismissed. That's not to say, however, that at the time you were stopped the registration was not current. Technically, you can still be charged for it, and the State can prosecute you for it - but in reality, it would be very rare for the State not to dismiss the charge upon a showing of proof of current registration.