Writing for The Playlist, Jordan Ruimy wrote that it "feels like the culmination of the last 50 years of horror".
USA Today called it a "modern-day horror masterpiece" while The Hollywood Reporter simply said: "Bone-chilling."
Viewers at the film's first screening at Sundance earlier this month took to Twitter to say there would be "no scarier movie this year".
HEREDITARY is so disquieting, you’ll be gasping for air in the theater. Utterly believable supernatural horror. There will be no scarier movie this year. If there is, it means we’re in a new golden age. #Sundance
HEREDITARY isn't just the freakiest thing I've seen in ages, but by far the most emotionally upsetting. Never feels like a tease; every scare has a very cruel purpose. Toni Collette astonishes. Couldn't have asked for a more satisfying end to my #Sundance2018.
HEREDITARY chilled me to my bone. It's pure emotional terrorism, gripping you with *real* horror, the unspeakable kind, and then imbuing the supernatural stuff with those feelings. I loved it/resent it for the nightmares I'm going to have. #Sundance2018
I was so unprepared for how great HEREDITARY was going to be. Totally not into supernatural stuff, and I dug the hell out of it. Give Toni Colette all the awards please. #Sundance2018
— Heatherween III: Season of the Wixson (@thehorrorchick) January 23, 2018
In all my years of coming to Sundance I’ve never taken in multiple viewings of a film… until @A24's HEREDITARY. Ari Aster's 2nd masterpiece (the 1st: his short THE STRANGE THING ABOUT THE JOHNSONS) is horror perfection with astounding performances by Toni Collette & Alex Wolff.