A search will resume on Monday morning for two senior executives from a private insurance company who failed to return from a bushwalk in the Blue Mountains.

Chris Dalton, 57, from Chatswood, and Paul Bates, 58, from Mosman, set out together on Saturday morning for a day-long hike at Mount Wilson, 14 kilometres east of Bell in the Blue Mountains.

The men work together at private healthcare group Bupa Australia, where Dr Bates is the chief medical officer for Australia and New Zealand, and Dr Dalton is a medical director.

Dr Bates has previously held leadership roles at health companies around the world, while Dr Dalton was formerly an ear, nose and throat surgeon at the Sydney Children's Hospital.

The men's families raised the alarm when they failed to return home on Saturday night, sparking a search on Sunday in an area of bushland that police described as "rugged".

On Sunday, police found the men's car parked next to the Mount Wilson fire shed.

Emergency services, including Blue Mountains police, the Westpac Life Saver Helicopter, Police Rescue officers and NSW Ambulance Special Operations officers, searched in the area around where the car was found on Sunday but found no trace of the men.

Both men are believed to be fit and active, and have some experience in bushwalking.

A NSW Police spokesman said the search was called off at nightfall on Sunday.

He said search crews would attend a briefing at 8am on Monday at the Mount Wilson fire station before the search resumes.

Police said the men had only planned to go for a day trip, and were not believed to be carrying supplies to spend several nights in the bush.

They did not log their walk with the National Parks and Wildlife Service.

Brooke Lord, a spokeswoman for Bupa, said Dr Bates and Dr Dalton's colleagues were extremely concerned.

"We are hugely concerned and our thoughts are with Paul, Chris and their families," she said.

"We're remaining very hopeful for a positive outcome today."

Police urged anyone with information about the men's location to contact triple-0 immediately.