Police are reviewing the search for missing man Scott Murphy, who was last seen near Loongana in North West Tasmania on Saturday morning.
Inspector Steve Jones said search parties had covered a variety of terrains over the past five days.
"Despite our considerable efforts using specialist resources of police search and rescue members, SES volunteers, civilian volunteers on motorbikes and horses, as well as the Tasmania Police Westpac Rescue Helicopter and a drone, police hold grave concerns for Mr Murphy's welfare," he said.
"A thorough search review is being conducted to re-evaluate any significant leads however we must be realistic at this stage."
"We remain in close contact with Mr Murphy's family and our thoughts continue to be with them at this difficult time."
Anyone who has seen Mr Murphy since Saturday morning, or who has information about his current whereabouts is asked to contact Tasmania Police on 131 444.
