Donald Macdonald, 46, from the Point area of Lewis was found seriously hurt on the shoreline by a rescue helicopter.
He was being treated for head and spinal injuries at Western Isles Hospital in Stornoway. The emergency services were called before 4pm after a report that a man had vanished from the cliff edge while out gathering sheep near the village of Swordale.
The Stornoway-based coastguard rescue helicopter arrived at the sheer cliffs with the town's lifeboat and a coast rescue team.
A coastguard spokesman said: "The casualty was found by the helicopter and the lifeboat fast rescue boat went to where he was and took him out of there."
He added that the cliffs where Mr Macdonald fell were up to 200ft above the shore.
Mr Macdonald stayed with his mother in the village. He had two older brothers, one of whom works in the hospital he was taken to.
A villager said: "We are all in shock. We really feel for his family.
"Donald was working on the mainland but gave up his job and came home to look after his mother when she became unwell.
"These cliffs at the shore in this area are very high and very dangerous. We heard he was looking for his brother's ram when he fell."