$re = '/(AAA|BBB|CCC|DDD)\((([^()]*|\([^()]*\))*)\)/';
$str = 'one two 12AAA(CCC(C1_1);A1_1;DDD(145))dfg
dfgdfgdfg,BBB(B1_1; CCC(C1_1); B1_2) sfsgndf
dfgnhjdfglkjdfg DDD(D1_1)
CCC()
one two 12AAA(CCC(C1_1; DDD(D1_1));A1_1)dfg ';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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