I bought one of these because a friend (also a Mac user) had one and it worked well when I saw it in action. He'd had some difficulty with an antivirus program at first, but was pleased with the product when he worked round the problem. My own story is less happy. I found the drive impossible to initialise on a Mac (latest OS), so I sent it back and got a new one. Same problem with the new one. I spent a long time exchanging emails with the IronKey help desk, who suggested, inter alia, that I must have bought secondhand products from Amazon! In the end they admitted there was a software problem currently being addressed. So I now have a very nice key fob until I can find an up to date Windows machine on which to do the initialisation, something I haven't had time for as yet. It's obvious that the build quality is very good and I know that these things work on Mac from my friend's experience, hence the two stars, but I'd warn Mac users to be wary of this product until the software is sorted.