Drug repurposing involves identifying new therapeutic uses for existing medications. The guiding principle behind this book is to present drug repurposing as a promising avenue in modern healthcare. It not only minimizes the time and cost of the development of the drugs, but it also assures safety and minimizes the risk of pharmaceutical resistance. The editors have organized the book around new therapeutic strategies for the treatment of various diseases including fungal infections, diabetes, neurological disorders, breast cancer, non-small cell lung cancer (NSCLC), and kidney diseases. For centuries, natural compounds have been used to treat different diseases with minimal or no side-effects. Therefore, many clinically approved natural products are now being explored for their potential in treating new diseases. This book presents a variety of drug repurposing approaches for various therapeutic applications.