Hi Dean: Well, that varies, person to person. Also, depends what you mean by grow back - 1/2"? 8"? I'd say in general, once you finish chemo it takes about 6 months for your hair to grow back enough that you don't look like you've got a boys' haircut. And be aware it might (probably) will grow back different than it was— a different color, wavy if it was straight, straight if it was wavy... it's like your hair says, "YEAH, a new life, let's try something different!" It's interesting for sure... Good luck - PJH