Technical Abstract: Research on Marek's disease (MD) has accomplished a great number of successes within the last 40 years. Development of a rather efficacious system of control is one of the most relevant achievements in avian diseases as MD has the potential of being devastating for the poultry industry. MD control is based on three criteria: good biosecurity, selection for genetic resistance and vaccination. Biosecurity and genetic resistance are currently used as important adjuncts to vaccination rather than as primary control strategies. Despite the high efficacy of the vaccines, MD is still a major concern for the poultry industry. The current system of control sometimes fails and unpredictable outbreaks continue to occur. Also, currently available vaccines do not prevent the evolution of MDV into more virulent forms that are difficult to protect (Witter, 1997a). Finally, because of the cell-associated nature of MD vaccines, the cost associated with the handling and administration of the vaccines is still high. With better knowledge on the chicken genome and the progress in the study of molecular biology of MD, it is likely that new approaches to the MD control will be pursued. Recombinant vaccines and MD resistant transgenic chickens might be useful tools in the future. However, these new solutions are not feasible until more basic knowledge on the virus, host and MD pathogenesis is available. Also, improving current MD control methods will require the commitment of research institutions, biological and breeder companies, and this process will neither be easy nor cheap. Finally, the new solutions have to be widely accepted by the public and, in the case of genetically modified products, this might not occur.