Darien Immediate Care is an urgent care center in Darien, located at 8190 S. Cass Ave Darien IL 60561. They are open 7 days a week, including today from 8:00AM to 2:00PM seeing walk-in patients with non-emergent healthcare conditions. Unlike most urgent care and walk-in clinics, Darien Immediate Care offers you the ability to book online in advance through Solv prior to arriving at the clinic..