Seven Poles and one Filipino were on board the Cypriot-registered Cemfjord, a cargo ship carrying cement, which capsized around 15 miles (24 kilometres) from Wick on the northeast tip of Scotland.
"The search has resumed this morning, with two helicopters, four lifeboats and five coastguard rescue teams. There is no sign of any of the crewmen," said a spokeswoman for the Maritime and Coastguard Agency.
"It is early in the day so we will see how the day progresses, but every effort is under way."
A passing ferry spotted the upturned hull at around 1430 GMT on Saturday. Its last-known position was at 1315 GMT on Friday.
Brise of Hamburg, managers of the cement carrier, confirmed in a statement that the crew of eight were missing "following a severe accident".
"No distress call was received from the vessel. Bad weather prevailed in the area at the time and conditions remain difficult at the scene, with storm force winds.
"The crew consists of seven Polish seafarers and one Filipino mariner. The company is in the process of informing the families."
Built in 1984, the 83-metre vessel successfully completed her classification renewal inspections during December, Brise said.
It was carrying a cargo of 2,000 tonnes of cement from Aalborg in Denmark to Runcorn near Liverpool on the northwest English coast, right round the top of Britain. It had been due to arrive on Monday.