note Anonymous Monk The following is just not working. Basically, i want to match a value that has "equity",but NOT "private equity". The result must be items 1, 2, 4, 5. Please check this out: <code> my %hash = ( 1 => 'equity, private equity', 2 => 'equity', 3 => 'private equity', 4 => 'private equity,equity', 5 => 'private equity, equity', 6 => 'equity,private equity', 7 => 'private equity', 8 => 'mutual funds', 9 => 'cds' ); while (my ($k, $v) = each %hash) { next unless $v =~ m/(?!private\s+)equity/; printf("%d -> %s\n", $k, $v); } </code> 518444 518444 2