Zanotti was playing the 16th hole, his seventh of the opening round at the Kennemer club, when he was struck by a ball hit from the 14th by Alexandre Kaleka. The incident caused the tournament to be suspended for nearly two hours.
An ambulance drove onto the course and medics treated the 31-year-old Zanotti before driving him to a nearby hospital.
The European Tour said on its website that Zanotti never lost consciousness and was taken to the hospital as a precaution.
"The latest report from hospital is that all neurological tests have come back clear. We wish Fabrizio a speedy recovery," said Miguel Vidaor, the tournament director for the European Tour.
Players Felipe Aguilar and Ricardo Gonzalez accompanied Zanotti to the hospital. All three players withdrew from the tournament.
Zanotti, who won the BMW International Open in June, had one bogey and a birdie to put him at even par when he was hit.