Police seized 10,000 valium tablets during a drugs raid on a property in Nelson Street in Largs this month.
A 43 year old man has been arrested in connection with the discovery, which has a street value of £10,000.
Inspector Colin Convery of Largs praised his officers for the operation which took place on Friday January 5, and said: "It was a significant recovery which was achieved through a warrant as a result of good policing intelligence, and help from the local community."