rkkwan - We actually did recharge the cards once during our visit (very easy to do; I think all the main subway stations have the recharging machines.) We did not want to recharge the cards again because we did not want to have excess Hong Kong dollars to use up, or trade in for US dollars at a lousy rate. We are headed back to Hong Kong in a month and we will definitely be getting Octopus cards again. Wish all major international cities had a similar card.