Leishmaniasis is a parasitic disease that is endemic to American, African, Asian and southern European countries. More than 350 million individuals in 88 countries are at risk of infection from this neglected tropical disease. No effective vaccinations are available against leishmaniasis, and control of the disease relies entirely on toxic drug treatments, some of which were developed as early as the 1940s. As parasite resistance becomes more prevalent, there is increasing concern that currently used drugs will soon become ineffective treatments. Consequently, an urgent need exists to search new classes of compounds that are active against the parasite. Phenolic compounds have positive effect on the human health with many recently published studies reporting anti-inflammatory, cardio protective activities, anti-allergic, anti-microbial, anti-carcinogenic and UVf iltering properties as well as antioxidant properties. This book emphasises on potential leishmanicidal activity of caffeic ferulic, syringic and 4-hydroxybenzoic acids.