Does Amsterdam have a subway system to go to the nearest downtown centre. I have 3 hrs at airport.?

3 hours probably isn't enough time. I once had a 7 hour layover there so we got out into the city and had lunch and beer. There is a subway train station and I think it is right in the airport. Not long after leaving the airport it becomes an elevated train. If you just want to see Amsterdam, maybe you could go out and turn around and come back to the airport.

No, the train goes over land.

Three hours will not be enough time. You have to arrive back at the airport at least an hour before your flight time. It takes about 25 minutes each way on the train.

Add to that the time to get to the train from your flight, any delays in your flight, and you'd have about 20 minutes to see the sights.

You obviously mean you have a 3 hour 'layover' at Schipol Airport, if so, forget about going anywhere. Nowhere near enough time. Good news is that there is more than enough shops pubs and cafes (and even a small museum)to keep you amused for your 'layover' time.

There is a subway train station that gets you from Schiphol airport directly to Amsterdam Centraal; but nonetheless, I'd say that three hours isn't worth the time to get there and back. Just enjoy the Schiphol area with a Heineken beer and a burger at McD's. I know they're overpriced at the airport, but that's about the choice you have. Schiphol is, well, not actually out in the woods, but out in the Northern Sea. If you got a window seat, look out. The landing approach is quite an experience; if you're afraid of flying, choose a seat near the aisle.

Stay at the airport, 3 hours isn't enough to go anywhere. Plus it's a huge airport and you'll need at least 20 minutes to get to either of your gates.

Amsterdam does have a Metro (=subway) system, but it doesn't run to Schiphol airport (yet - the North/South line currently scheduled for completion in 2013 may eventually reach there). The airport does however have a Nederlandse Spoorwegen (Dutch Railways) station with trains running to Amsterdam Centraal station quite frequently, but as others have said, three hours isn't long enough for you to do anything and get back in time to check in for your ongoing flight. Stay at the airport and spend your money in the shops there!

You will have enough time to get to town to have a smoke and get back on the train and go back to the airport. I would do it. It's better than starring out the window wishing you were doing something more exciting. And There's places to go right across the street from central station.