Carnitine deficiency and carnitine supplementation are reported in many other diseases introduced in this book so far. Also, there are no good therapeutic drugs or means for these diseases, and future studies on the potential for treatment of these diseases are needed. In this chapter, I will briefly introduce several studies related to carnitine deficiency/insufficiency and carnitine supplementation in influenza-associated encephalopathy, ALS, chronic fatigue syndrome, inflammatory bowel disease, alcoholism, ADHD, autism, and infertility and discuss the possibility of carnitine to treat these diseases in the future.