This OCaml-library interfaces the C-library PCRE (Perl-compatibility Regular Expressions). It can be used for string matching with "PERL"-style regular expressions. The PCRE-library by Philip Hazel has been under development for many years and is fairly advanced and stable. It implements just about all of the functionality that can be found in PERL regular expressions. The higher-level functions written in OCaml (split, replace, etc.), too, are compatible with the corresponding PERL-functions to the extent that OCaml allows. Most people find the syntax of PERL-style regular expressions more straightforward and powerful than the Emacs-style regular expressions used in the Str-module in the standard OCaml distribution.