Laptops, handbags and cash have been among items stolen during a series of thefts from vehicles in Aylesbury.
A total of 24 incidents have occurred between December 20 and February 15, with the Elm Farm, Mandeville and Walton Court areas the main targets.
The thefts have taken place when thieves have smashed vehicle windows.
Sgt Andy Jones said: “I would remind car owners not to leave valuable items on show in their cars as this is an invitation to thieves.
“My advice is not to leave anything on display and make sure your car is empty of items such as iPads, phones, wallets, purses, handbags and cash.
“I would like to hear from anyone who might have witnessed these offences. It is possible that someone heard car windows being smashed or saw someone leaving the scene.”
Anyone with information should call police on 101 or Crimestoppers anonymously on 0800 555 111.