Repeat breeding of cows is a source of frustration and economic loss to the dairy producers. It is one of the main reasons of infertility and has long been a problem world wide. Although various factors are responsible for repeat breeding, one factor that contributes greatly is improper oestrus detection and untimely AI. This book, a part of PhD thesis of Tamil Nadu Veterinary and Animal Sciences University, Chennai, India, explores the possibilities of using oestrus synchronizing agents along with ovulatory hormone in fertility enhancement of repeat breeders. Various oestrus induction protocols, endocrinological back ground and fertility rates are studied and presented in an elaborative manner. Further, effect of post-AI hCG injection and use of adjuvant to antibiotics in repeaters along with histopathology of endometrium are explained with data. These factors make this book more useful to the researchers in theriogenology, UG and PG students and teachers of veterinary science and practicing veterinarians globally.