Patients who take crutches, walking frames or sticks from Bath's Royal United Hospital and do not return them are risking a fine.
From August anyone who borrows a walking device and does not return it when no longer needed will be fined £35.
It costs the RUH about £37,000 a year to supply walking aids to patients, with crutches costing £20 a pair and walking frames £26.
By returning unneeded walking aids patients will help the hospital to save money.
Physiotherapist Andrew Ross said: "Physiotherapy supply the emergency and orthopaedic departments with crutches and frames, and these are loaned to patients for a short time. Some are returned but we know that many are not, which is why we end up having to buy £37,000 of walking aids each year.
"If you borrow a book from a public library you are expected to return it – it is the same principle for the hospital."
Patients will be asked to sign for the loan of a walking aid, which asks for them to be returned within a 12-week period. If they are required for long-term use that will be recorded on the form.
Anyone who does not return the aid within that time will be sent an invoice for £35, which covers the cost incurred in replacing them as well as administration costs.
Mr Ross said: "By returning them people will be helping the trust to save quite a lot of money.
"It is a significant sum which could effectively be used to employ a senior nurse or senior physiotherapist for a year."
If former patients do have any walking aids loaned by the RUH they can return them before August and will not be liable for a fine.
They can be taken to the reception area at the physiotherapy department any time between 9am and 4pm.