The AtlasJet website will not accept either my US Mastercard or US Visa. Is there a trick to this? I'd rather do it direct than through a travel agent. Thanks.

Have you called your CC issuer to ask if they are blocking the transaction for some reason?

That's what I would recommend, also. I have some credit cards (American) that automatically block any charge from a foreign country, even if it is some place like France or UK. In this case, the company is in Turkey, so seems even more likely that the card issuer could just be blocking it.

I recently paid with Visa on Turkish Air - Visa has a new "verify by Visa" feature with certain vendors, and you need to verify your card. It's an easy step done online, just once...call your credit card, not sure if AtlasJet is one of these vendors.

I ended up getting tickets with Turkish Airlines and had no problem with my cc. Two roundtrips Istanbul-Antalya were 394 TL instead of the 349 with AtlasJet.

Caution! I did pay with my visa card for flights booked several months ago but recently got an email that they cancelled my flight from Istanbul to Kayseri...couldn't find one of their flights to rebook on so they said they'll refund my money (haven't gotten statement yet). However, while talking to the rep who called to confirm my cancel, he noticed that I also was booked on Dalaman to Istanbul and informed me that flight was cancelled also. So, with short notice, I had to book business class on Turkish Air for the first flight and booked a more expensive flight than I could have gotten had I gone with Turkish Air in the first place. At least I found out before I was in Turkey. i'd give them a miss.