$re = '/^\s*\bMAIN LEVEL\b\n(?:(?!\n\n)[\s\S])*\bBedrooms:\s*(.*)/m';
$str = '
MAIN LEVEL
Entrance: 11
Living: 22
Dining: 333
Kitchen: 444
Family: 555
Bedrooms: 666
Den: 777
SECOND LEVEL
Entrance: 1111
Living: 2222
Dining: 3333
Kitchen: 4444
Family: 5555
Bedrooms: 6666
THIRD LEVEL
Entrance: 3333
Living: 334
Dining: 3332
Kitchen: 33336
Family: 33332
';
preg_match_all($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