A spokesman for Francois Gendron said the deputy premier would spend Wednesday night in a Quebec City hospital.
Gendron, 69, has represented the northwestern Quebec riding of Abitibi-Ouest in the legislature since 1976.
Health Minister Rejean Hebert, who is a doctor, decided to call an ambulance even though he did not believe Gendron was having a heart attack.
"I didn't want to take a chance and that hypothesis had to be eliminated," Hebert said.
Gendron, who is also agriculture, fisheries and food minister, recently had mouth surgery. Hebert said he does not believe Wednesday's health scare was related to that.