Ed, many folks do recommend vaccination for Mareks. But there is an other side of the coin. The vaccine does not prevent the disease. It prevents the complications from it. Turkeys carry a less virulent strain of Mareks, so if you have a population of wild turkeys, or even get some domestic ones, in theory, your chickens will reap immunity benefit from that. In the book by Harvey Ussery: The Small-Scale Poultry Flock: An All-Natural Approach to Raising Chickens and Other Fowl for Home and Market Growers, he speaks to the issue of Mareks. In summary, he states that a healthy flock is not likely to be affected by Mareks. They may contract it, but are more likely to shrug it off. I know that many readers will jump on this post with plenty of testimonies stating otherwise. I'm merely passing along his stand on the issue (paraphrased b/c I don't have time to quote the reference right now.) So, a vaccinated back yard flock IS not immune to Mareks, and can pass it on to unvaccinated chicks that may come along in future generations. A flock that is not immunized, may have a few birds wiped out by the disease. But the remaining strong ones who have been infected, and do not become very sick are resistant to the disease. (not immune) Over time, that flock will build a strong resistance to Mareks. I have a good population of turkeys that pass through my yard. I choose not to vaccinate. Have not yet seen any signs of infection. But, if that becomes an issue, since it's my goal to build my own land race flock that will thrive in my climate and conditions, I think I'll go the natural selection route.