Jason Priestley -- Hospitalized After Scary Fall From Horse

Jason Priestley was hospitalized after being thrown off of a horse on the set of his show, "The Code."

We're told he fell hard Monday and then beelined it for the ER. He stayed in the hospital overnight because he says he has a history of concussions and a neurologist needed to noodle over the impact of the fall. Turns out he did indeed suffer another concussion.

Jason's had his share of mishaps. He fractured his spine and suffered a concussion back in 2002 during a race car crash in Kentucky.