Under the Reciprocal Enforcement of Judgments Act, there is a simple procedure to enforce judgments arising out of the courts of the common-law provinces. By “common law provinces”, I mean all the provinces except Quebec (the province of Quebec has a civil law system).
Enforcing a judgment from Quebec is similar to enforcing a judgment from any foreign jurisdiction. Basically the common law principles for enforcing judgments apply. This includes ensuring that the foreign court had jurisdiction to grant the judgment. Additionally, the judgment must have been properly obtained under the rules of the foreign court and the court must adhere to the principles of natural justice. If these principles are satisfied, then the likelihood of a Quebec judgment (any foreign judgment for that matter) being enforced in Ontario is high.
For a recent example, see the case of De Abreu v. Bayley 2012 ONSC 5445. Here, the court granted the order to enforce the Quebec judgment even though the defendant was not served personally. She was served by substituted service. The court was satisfied that the rules of the Quebec court had been followed.
Prior to enforcing any foreign judgment, it is important to address any potential issues of fairness, as this will be a concern for the court.