If you're talking about unicode files, try using
binmode FILEHANDLE,":utf8"; (please use perl 5.8.0 if you're not doing that right now, it is reported to have better unicode support than the older versions that support it)
See the binmode entry in perlfunc, perlopentut and perlunicode.
Don't know much about unicode tho' - YMMV.
Joost