$re = '/<label .*?>(.*?)<\/label>/';
$str = '<label class="s-nav right" for="s-22">simply</label>
<label class="s-nav left" for="s-21">dummy</label>
<label class="s-nav right" for="s-23">text</label>
<label class="s-nav left" for="s-22">of the printing</label>
<label class="s-nav right" for="s-24">and typesetting</label>
<label class="s-nav left" for="s-23">industry</label>
<label class="s-nav right" for="s-25">Lorem Ipsum</label>
<label class="s-nav left" for="s-24">Ipsum</label>';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php