One 10-year-old boy was treated for suspected spinal injuries, while another three people had head injuries.
The rest were being treated for lower leg injuries.
Thousands took part yesterday in the age-old Reek Sunday tradition in honour of St Patrick, who it is said fasted for 40 days on the Co Mayo mountain’s peak in 441AD.
Personnel from several groups including Civil Defence and Mayo Mountain Rescue were on hand to provide assistance to walkers.
Mayo Mountain Rescue said visibility at times was as low as 20 metres.
Peter Jordan, chairman, said visibility was so poor that the Air Corps helicopter was grounded and unable to come to their assistance.
“The conditions were pretty terrible, but at least it wasn’t cold. It was quite warm up there. We’re not having many cases of cold or hypothermia. It’s very slippy under foot.” Mr Jordan said.
Gardaí estimated around 20,000 people took part in the walk.
Civil Defence branded the conditions “desperate”, but Mr Jordan said they were not as bad as last year when walkers were battered by wind and rain. Mass was celebrated at the summit at 8am, then every half-hour until 2pm.
The Archbishop of Tuam, Dr Michael Neary, spoke to pilgrims of the importance of maintaining the faith that had kept the tradition alive through many difficult centuries.
He said that faith was never more important than at a time of much doubt and uncertainty and concern for the future.