The search was launched after the walkers became disorientated because of poor weather conditions on the summit of Ben Nevis in the Highlands, police said.
Police Scotland and Lochaber Mountain Rescue Team are co-ordinating the search, which is being resumed today.
Heavy snow affected several parts of Scotland yesterday, with blizzard conditions reported on higher ground.
Snow gates were closed Braemar, Spittal of Glenshee and Cockbridge - Tomintoul.
Reports of the search came as the Scottish Government issued a warning to walkers and climbers.
Minister for Sport and Commonwealth Games Shona Robison urged the public to be careful when visiting Scotland’s hills and mountains, with avalanche warnings in place across a number of popular destinations.
“It doesn’t matter if it’s your first or one thousandth trip to a mountain you must prepare properly and check the weather and avalanche conditions as close as possible to departure,” she said.
“The majority of walkers and skiers have safe and enjoyable trips but lives can be easily lost. Scotland’s snow topped scenes are as potentially deadly as they are beautiful.”