Police said the cause of death was not immediately apparent, but they ruled out foul play, reported Us magazine.
"We know there will be considerable interest in this case, and we have detectives assigned to the case who attended with our Forensic Identification Unit to examine the scene, to ensure to the extent possible that there are no unanswered questions," Vancouver Police said in a statement.
Monteith had recently completed treatment for substance addiction. Earlier this year, the actor checked rehab, buoyed by the support of his girlfriend, Lea Michele.
After leaving rehab on April 26, he tweeted his fans, saying, "Sending out big love to everyone. Thank you for the continued support! It means the world to me!"
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Monteith also starred in 'Final Destination 3' and 'Monte Carlo'. He and Michele, 26, had been dating for more than a year.
An autopsy is scheduled for tomorrow.
"The Coroner will be determining the next steps with respect to establishing cause of death, but all indications are that there was no foul play," police statement said.