All eight retailers visited during an underage alcohol test purchasing operation in Cheltenham town centre successfully refused sales to an underage customer.
The checks were carried out on Saturday 31 October by Cheltenham Borough Council’s licensing team and Gloucestershire Police.
Police cadets attempted to purchase alcohol while plain-clothes officers observed the transactions.
Four of the eight premises had failed a previous operation in August, but all have now demonstrated improved compliance.
The council welcomed the results, saying they showed businesses were taking their responsibilities seriously.
Retailers are reminded that selling alcohol to anyone under 18 is a criminal offence and can lead to fines, prosecution or a review of their premises licence.