Officers made the discovery of cannabis at a property in New Street in Stonehouse, South Lanarkshire, at 8.30pm on Friday.
A 52-year-old man was arrested in connection with the find and remains in police custody.
A Strathclyde Police spokesman said: "Drugs with an estimated street value of three hundred and eighteen thousand pounds have been seized by police in Stonehouse.
"Officers searched a house in New Street, Stonehouse, under warrant and recovered the drugs believed to be cannabis."
A report will be sent to the procurator fiscal.