I found this bra completely comfortable, and I wear a 36 DD. If others are having difficulty with underarm rubbing, then it may be too small or normal irritation from sweat and exercise- try some athletic "slide" or Vaseline. The only complaint I have, is that it doesn't have adjustable straps. I have found another one that has hook and loop adjustable shoulder straps. I have just had the experience that over time, the straps will weaken and the fabric will stretch not giving the support it used to. Of course, this may be better, I haven't had it long enough.