Lions legend McGeechan collapses ahead of Test
"He has been taken to hospital," a New Zealand Rugby spokeswoman said.
"We're not quite sure what has happened but he has been suffering from a bug for the last few days, so it's not entirely clear whether his collapse today is related to that.
"We will let you know if we are able to pass on any further information."
An ambulance spokesman said a man had been taken to hospital in a "moderate" condition, but could not comment on the cause of the collapse.
McGeechan, 70, played 32 Tests for Scotland and eight for the Lions between in the 1970s and coached the Lions four times.
He is in New Zealand as part of a commentary team covering the current Lions tour.