In necrotic and retreatment cases, disinfection of root canal system is essential for successful root canal treatment. Due to the complexity of the root canal system, many areas of the root canal surfaces remains untouched during mechanical instrumentation. Therefore, a proper root canal irrigation solution is necessary during root canal instrumentation. Root canal iriigation solutions play an important role during root canal treatment. This book reviews comprehensively the major root canal irrigation solutions including sodium hypochlorite, chlorhexidine, MTAD, Tetraclean, iodine compounds, hydrogen peroxide, etc.