Newgal - I smoked during my first Master-Cleanse and of course I don't recommend it, but it's not as bad as not doing the Master-Cleanse at all. During a subsequent cleanse, I ran out of cigs and didn't smoke for a few days....then when I smoked two cigarettes again (while still on the MC) I felt violently ill. I thought, geez, this must be what my body feels like every time I smoke, but I've built up an immunity of sorts to it, so I'm not feeling the damage. I never smoked again and haven't even been tempted. Good luck!