St. Mary's Health Care, Metro Health and Spectrum Health — all in Grand Rapids — are also allowing only two visitors or relatives to visit a patient at one time.
Officials from the hospitals made the joint announcement Monday and said the restrictions will remain in place until further notice.
Staff at Spectrum Health will ask visitors if they are healthy. Spokesman Bruce Rossman said those who are not healthy will be "asked to not visit until they are feeling better."
The flu has hit at least 47 states.
Michigan-run labs have confirmed 338 cases at state-run labs. Four Michigan children have died.