The Royal Berks is only allowing "essential" visits to the hospital, after the winter vomiting bug Norovirus hit.
The hospital has released a statement, saying many patients are displaying symptoms of the virus already, and it has had to cut visiting times to reduce the chance of the bug spreading.
Dr Jonathan Fielden, Medical Director explains, "Every year we must manage a period of time when norovirus hits our community. We know that many schools, nursing homes and other workplaces are already affected and inevitably we are now experiencing issues within our Trust."
New hygiene measures have been brought in to try and control the spread of the bug, although the hospital says the only way to properly contain it is to reduce the number of people coming into the hospital to visit patients.
This means only "essential" visits will be allowed, for example, parents with children who are on peadiatric wards or close relatives to patients coming to the end of their life.
Some planned surgery at the hospital has also had to be postponed, although the disruption is only expected to last a few days.