Serial with interrupt

Hi,
I've a simple question. I would like to send and receive over the serial simultaneously. I think i should use an ISR for receiving over the serial. So i can offload the main loop of waiting the message coming, and do something else. There are some example out there. What I've found is not so clear. Maybe there is some of you already encountered in this problem.

Thanks

Marco

Serial input and output are already interrupt driven.

So i can offload the main loop of waiting the message coming

The loop() function should not be waiting for data. It should see IF there is data, and read (and store, if appropriate) whatever data there is. When there is sufficient data, it should do something with/about/to that data.