I always get mine vaccinated. It's not that much more expensive, and I have heard heartbreaking stories of those who's birds have fallen victim to Marek's to watch their beloved pet become slowly paralyzed and not able to eat or breathe or walk. Some recover, some don't. I'm not taking chances with all the effort I put into feeding and raising my baby chickens. You also never know what the wild birds are going to bring to your yard either. I also show my bantams, which is another concern for me since I take them elsewhere, the fear of them catching it.