The following is (hrrmph) difficult to understand. It was produced with a very recent build of droolsjbpm/master. rule "articles of a customer" when $c: Customer( 150 <= custid <= 250 ) $a: Article( $a1: artid, $a2: artname, custid == $c.getCustid() || == 3 ) then System.out.println( "Customer " + $c.getCustid() ); System.out.println( " Article " + $a.getArtid() + " " + $a.getArtname() + " by " + $a.getCustid() ); end Customer 3 Article 300 micro by 3 Customer 2 Article 300 micro by 3 Customer 1 Article 300 micro by 3 Customer 2 Article 300 speakers by 2 Customer 1 Article 200 mouse by 1 Customer 1 Article 100 keyboard by 1 -W