Diseases in intensive poultry flocks may occur due to viral, bacterial, fungal, protozoal, metazoan or arthropod infections or infestations. This chapter describes disease preventative measures, health monitoring and disease investigation techniques, and the management of sick meat chicken flocks. This chapter covers dealing with the emergency of an outbreak of disease in the flock, including hygiene procedures and methods of disposing of dead birds. The chapter examines the challenges inherent in poultry disease control and looks forward to future trends in this area.