Is it illegal or maybe discrimination to not let employees smoke on premise even if its not a smoke free enviroment?

Additional information
I guess I was pretty vague and I guess I wish it would be that easy to just go outside and take a "puff" but since the south dakota smoke ban is going to a vote Nov. 2010. I feel I should be able to smoke outside at work in an enclosed area which is out of sight. This is a country club and I am a sous chef working 60-70 hrs. plus a week. It is unthinkable to leave the property to have a puff and it is allowed for members who have said it isn't a problem for them if employees smoke.