Root canal treatment is a dental procedure that involves gaining access to the infected root canal space. Subsequently, the canal is chemo-mechanically debrided using endodontic files and antibacterial material (medicaments and irrigating solution), before it is obturated and permanently sealed with restorative material. Irrigation solution is used to cleanse and disinfect the root canal space to ensure all necrotic tissue debris, bacteria and their toxins are adequately removed. The complexity of the root canal system necessitates the use of an irrigant that is capable to reach canal irregularities and dentinal tubules to eliminate microorganisms residing in these areas without compromising the physical properties of the root dentin. Currently available irrigants have several drawbacks such as toxicity towards vital tissues, inability to remove the smear layer and results in untoward effect to the root dentin structure. The use of herbal plant extracts in alternative medicine has extended to the dental field and its potential in treating dentally related diseases have been widely studied. Orthosiphon stamineus (cat’s whiskers), Zingiber officinale (ginger) and Syzygium aromaticum (clove) are known for their antibacterial, anti-inflammatory and analgesic properties. With all the properties that they exhibit, these herbal plants have the potential to be used in root canal treatment. In this book, their effect towards the physical properties of the root structure (microhardness) and ability to remove smear layer were compared with commonly use irrigants and the results are discussed. The potentials of these herbal plant extracts in root canal treatment are encouraging and with further research, we are certain that it can be further developed as an alternative to replace the currently used irrigants in root canal treatment.