Police seized heroin, crack cocaine and Subutex from a home in Featherstone.
“A large quantity” of drugs were found hidden at the address, the town’s Neighbourhood Policing Team said on Facebook at 8pm on Monday.
Officers used a Magistrates Warrant to carry out the raid on the home, but its exact location is not known.
A man and a woman were arrested and enquiries are ongoing.
If anyone has information about drug dealing, police are urging people to call Crimestoppers on 0800 555 111.