This chapter discusses the intimate partnership between dairy cattle welfare and health. It begins by examining the welfare implications of common dairy cow diseases such as lameness, mastitis, metritis, acidosis, ketosis and other production-related diseases. It also addresses the impact of subclinical diseases as well. Stress and immune function is also discussed, followed by a review of how mental health can impact the welfare of dairy cattle. A case study on the health and welfare of cows in Indian shelters is also included.