Local police carried out their first ever drugs dog operation in Buckingham on Saturday night.
Police officers and special constables worked with dog handlers from Tyler Security to carry out a series of checks at pubs.
The drugs dogs alert their handler if a customer is carrying illegal substances or has been in contact with them.
The team visited the Whale, the Woolpack, the New Inn, the Three Cups, the White Hart, the Kings Head and 13 High Street.
Drugs, including cannabis and cocaine, were found in three venues.
One man has been cautioned for possession of a controlled substance.
Two other men were excluded from the town for the remainder of the night and will be interviewed at a later date.
Insp Emma Garside said the operation was a success and will be repeated.
She said: “All licensees were co-operative and welcomed our help to keep drugs out of their establishments.
“We shall be meeting with the licensed premises involved and will look to repeat this exercise again.
“Our message is quite simple, drug use and supply will not be tolerated.”