A 73-year-old hiker, missing in bushland on Fraser Island for three nights, has been found alive.

Madeleine Nowak had been hiking on the Fraser Island Great Walk with an organised tour when she became separated in the Valley of the Giants.

She had clothing and food with her and was understood to be in good health.

Police said they were notified after the woman found people at a campsite.

She was reunited with her husband this morning and will be flown to a nearby hospital for observation.

Police, National Parks and Wildlife, State Emergency Service and LifeFlight had all been conducting land and air searches.

More to come.