justcoder, может нужно указать кодировку?

авторIncredible thought it may seem, Java defaults to only understanding ASCII; it ignores its own native charcter set. So you always need to add “(?u)” to make case insensitivity work on normal Java text, which is Unicode not ASCII.
Also, if you expect things like \w to work on regular Java text, you need to add “(?U)”, which isn’t even supported until Java J.
In short, you normally want “(?iu)” for case insensitivity, and you want “(?U)” for the UNICODE_CHARCLASSES flag.
Note that this is still only the simplistic kind of case insensitivity as provided by the Character class, not full casemappings such as provided by the String class. That will be ok for Spanish and Portuguese, but not for German or Greek.