The Department of Health said it was liaising with an NGO to find a solution to the problem at RK Khan Hospital in Chatsworth.
The monkeys apparently come into the wards through open windows.
During breakfast, they are apparently seen in large groups looking through the windows.
They return again during visiting hours, between 3pm and 3.30pm, when patients receive food parcels from their relatives.
The patients’ lockers at the hospital cannot be closed or locked, apparently making it easy for the monkeys to come in and grab fruit and other food.
A former patient, Wendy O’Niel from Chatsworth, said she watched monkeys come into the wards during her nine-day stay at the hospital.
“The monkeys took all my fruit and bags of food. They come in through the window. There is nothing the nurses can do about it,” she said.
O’Niel added that the monkeys had learnt what the “perfect time” was to come in to steal food.
Salome Kisten, a fruit seller outside the hospital, said the monkeys were also affecting her business.
“They try to grab all my fruit here in the morning and again at 3pm during visiting hours,” she said.
She has resorted to using water guns to try to keep the monkeys at bay without hurting them.
Hospital chief executive officer Dr Prakash Subban said he was aware of the problem and that steps had been taken to address the issue.
Ncumisa Mafunda, Department of Health spokesperson, said: “Management of RK Khan Hospital is in contact with the relevant NGO in a bid to find a solution to manage the intrusion of monkeys into the facility’s premises.”
She said the department apologised for any inconvenience caused by the monkey intrusion.
Steve Smit, co-founder of Monkey Helpline, said they had been in contact with the hospital and planned to meet with its management this week.
“We have solutions to offer them, but it will be up to management to have the will and intent to implement them,” Smit said.
He said the hospital was in monkey territory, so the primates would always be in the area.
Smit was concerned that the monkeys might be in danger of getting sick from eating out of hospital bins that might also be used to dispose of used medical instruments.