PerlTeX is a combination Perl script (perltex.pl) and LaTeX2e package (perltex.sty) that, together, give the user the ability to define LaTeX macros in terms of Perl code. Once defined, a Perl macro becomes indistinguishable from any other LaTeX macro. PerlTeX thereby combines LaTeX's typesetting power with Perl's programmability. PerlTeX will make use of persistent named pipes, and thereby run more efficiently, on operating systems that offer them (mostly Unix-like systems). Also provided is a switch to generate a PerlTeX-free, document-specific, noperltex.sty that is useful when distributing a document to places where PerlTeX is not available.