[neverending]

I'm surprised some of these films have not been named:

Shock Corridor (1963)
http://www.imdb.com/title/tt0057495/
This is a MASTERPIECE directed by Sam Fuller, about a reporter who gets himself committed so he can write a Pulitzer prize article. There are some really creepy scenes in this movie.

Cabinet des Dr. Caligari., Das (1920)
http://www.imdb.com/title/tt0010323/
One of the great silent horror movies. An insane asylum director performs hipnotic experiments on a subject, making him committ murders.

Marat/Sade (1967)
http://www.imdb.com/title/tt0060668/
The full title of this film is "The Persecution & Assasination of Jean-Paul Marat as Performed by the Inmates of the Asylum of Charenton Under the Direction of the Marquis DeSade." This movie is not for everyone. It's the filmed version of a play in VERSE- but it does all take place in an insane asylum and is about a group of inmates puttingf on a play about the assination of Jean Paul Marat, one of the leaders of the French Revolution. This is an AMAZING movie- one of my all time top 5. Has Patrick McGee, Ian Richardson & Glenda Jackson.

These two films I have not seen, but from their description on IMDB they sound promising:

Asylum of Satan (1975)
http://www.imdb.com/title/tt0068231/

Shock Treatment (1964)
http://www.imdb.com/title/tt0058585/