Most likely too small. I'm 5'10.5" and I ride an 18" in most brands. Of course if you can test ride it then find out for yourself. It may fit you like a glove. I just wouldn't risk buying it if you can't ride it first since it will most likely be too small.

Now saying that, the main measurement I worry about is top tube length. See if the top tube is close to what your current bike is.