Based on your @INC, one thing that may be worth checking is the following. HTTP::Request requires HTTP::Message, which in turn potentially requires a number of other modules (one can use scandeps.pl to see which ones). The pure Perl modules such as HTTP::Headers are presumably available under /the/full/dir/path/8080/cgi-bin/usr/local/lib/perl5/site_perl, if not under the system /usr/lib/perl5/ tree, but there's some XS-based modules, such as MIME::Base64 or Compress::Zlib, that may also be needed. Such modules normally get installed into an architecture-specific subdirectory, such as i386-linux-thread-multi. The lib module will add such architecture-specific directories to @INC for you, but they don't seem to be present in your /the/full/dir/path/8080/cgi-bin/usr/local/lib/perl5/site_perl tree. If modules such as MIME::Base64 and Compress::Zlib are not available under the system /usr/lib/perl5/ tree, are they present in your /the/full/dir/path/8080/cgi-bin/usr/local/lib/perl5/site_perl tree? If so, are they in such an architecture-specific directory? If they are available, but in a non-standard location, you may have to add such directories to your use lib statement.