A smoking ban could be lifted at the Royal Bournemouth Hospital following the discovery a number of patients are smoking in their beds.
Smoking was banned in and around the hospital's buildings in 2005.
But a review revealed it has been driven underground with staff, patients and visitors smoking in unsafe areas.
Karen Allman, human resources director, said: "We must not underestimate the risks of illicit smoking by patients in wards and enclosed buildings."
In her report to the trust's board of directors last Friday, she stated: "There was overwhelming evidence that staff found it extremely difficult to enforce the policy with patients and visitors.
"Staff were reluctant to approach smokers for fear of violent reaction and verbal abuse."
Ms Allman added: "Feedback clearly demonstrated that staff were also not adhering to the no smoking policy.
"Smoking by night staff was identified as a particular problem to contend with."
She anticipated that changes to allow smoking in designated areas outside the hospital buildings - such as allowing patients to smoke under supervision in the ward gardens at the Christchurch site - would be implemented towards the beginning of September, if the board agreed.