Thieves have stolen everything from officers' helmets and handcuffs to drugs and cash from police cars and stations.
In total, 29 items have been stolen from cars and stations in Leicestershire in the past three years.
They ranged from confectionery worth a couple of pounds to computer and communications equipment worth several hundred.
On two occasions, officers' helmets – each worth £50 – were stolen from police cars.
A set of handcuffs, valued at £23, was also taken from a car.
One station was targeted by thieves, who stripped lead worth £100 from its roof.
The list of stolen items, which have an estimated total value of £2,897, was released in response to a Freedom of Information Act request by the Leicester Mercury.
The force confirmed no police officer or member of staff was suspected of involvement in any of the thefts.
A city officer said: "People will always try to take advantage, whether it's someone passing through a station or someone we have sitting in the back of our cars.
"These things happen despite all the security at our stations and police officers' in-built suspicion of someone they've pulled over for questioning.
"Thankfully, it's never happened to me, because it's embarrassing to report that you've had something stolen from under your nose, especially your helmet or a set of cuffs."
Another officer said: "I've heard of stories of officers who've had things – sometimes small, personal items – nicked from their cars.
"On the surface, it sounds as though we have ignored our own advice about removing anything of value when you park up.
"But it might not always be when the officers are away from the car.
"When you have a suspect in the back of your vehicle at night and you're questioning them, they will have that opportunity to slip something into their pockets."
In its response, the force said: "It is important to note that the vast majority of these are crimes of opportunity committed by members of the public or detainees, as opposed to police officers and police staff.
"Having reviewed each of these incidents, no police officers or police staff were identified as a suspect and therefore were not disciplined.
"Any incidents that involved contracted staff resulted in their dismissal and separate disciplinary proceedings would have been initiated by their agency."
