The Cottage Ward at Leek Moorlands Hospital is expected to be closed to new patients for at least a week.
A number of patients and staff have reported flu-like symptoms although evidence of the virus is yet to be confirmed.
An NHS spokesperson said they regretted having to close the ward but added that other wards were still open.
Director of nursing and quality, Siobhan Heafield, said: "It is important that we make all possible efforts to limit the spread of the virus.
"Other wards are not affected and they and our routine clinics and the minor injuries unit continue to operate as normal.
"Winter has arrived rather late this year and the recent cold weather has increased the level of flu-like illness and those at risk of getting serious complications from flu may be more vulnerable if they haven't yet had the flu jab."
A ward at a Staffordshire hospital has been closed because of a suspected flu outbreak.