The Santa Rosa Mental Health Institute is a mental health treatment and care facility. It is located just outside of Los Angeles, California.
- Hugo "Hurley" Reyes: Hurley was probably originally admitted for psychosis (relating to seeing Dave) and for being in a "near-catatonic" state after the collapsing deck incident (actual diagnosis unknown). He was treated with clonazepam. He returned to the institution after he was rescued from the Island, suffering from visions of Charlie, which cause him to "freak out."
- Walt Lloyd: He was admitted sometime after 2007 under the name of Keith Johnson (actual diagnosis unknown). He left with Benjamin Linus and Hurley to return to the Island following Hurley's appointment as Protector.
- Leonard Simms: He was visited by Hurley and repeats the Numbers over and over.
- Emily Locke: Locke's mother was treated for schizophrenia and was eventually released.
- Libby: She was admitted after the death of her husband (Actual diagnosis unknown)
- Lewis: He appears to be friendly with Hurley. He also may have been able to see Charlie, even though Hurley is convinced that it was a hallucination.
- An unnamed patient in "The Beginning of the End".
- The actual filming location took place in two areas: The exterior shot of Hurley/Charlie/The Tree was at Windward Community College, at the Hakipu'u Learning Center, while the interior shot was filmed at the Laniakea YWCA next to 'Iolani Palace in downtown Honolulu.
Bloopers and continuity errors
- The name of the facility has been variously given as "Santa Rosa Mental Institute" and "Santa Rosa Mental Health Institute".
- In "The Life and Death of Jeremy Bentham", a location card states the Santa Rosa Mental Health Institute is in "Santa Rosa, CA", which is over 400 miles away and many hours' drive from Southern California. This conflicts with the previously established canon which places the facility outside Los Angeles.
- The newscaster reporting the murder of the man sitting outside the Institute stated "The victim was found shot in his car on the grounds of the Santa Rosa hospital, a private mental health care facility outside Los Angeles". ("Because You Left")
- Sayid would not have been able to spring Hurley from the Institute if it was located in Santa Rosa, and still make it to the safehouse in Los Angeles later that same night. ("Because You Left")
- Jack visiting Hurley after work at St. Sebastian Hospital in Los Angeles and returning home the same evening would be logistically improbable if the Institute was located in Santa Rosa, California instead. ("Something Nice Back Home")
- Hurley's home in Los Angeles is shown to be close enough to the Institute to arrive the same day during the same time of day. ("The Lie")
- The Institute is shown to be out in the countryside. While Sonoma County (the location of Santa Rosa, California) in real life includes lots of unincorporated countryside and foothills, the city of Santa Rosa, California is a significant metropolitan area.