Roadsides are habitats with very specific environmental conditions, often substantially differing from their natural surroundings. Roadside trees provide a home for many floral and faunal species and have many environmental benefits including removing air pollutants, supporting wildlife, etc. Many medicinal plants including roadside trees have been discovered and traditionally they are being used for treating many kinds of diseases. Phytochemicals are chemical compounds that are usually secreted by the plants for performing functions like defense against insects, fungi, diseases, and animals that feed on them. These phytochemicals with potential biological activities have been identified from various plant species, yet many of the medicinal potency of the plants remain unexplored. Modern knowledge of the potential value of medicinal plants has made it possible for researchers and medical practitioners to use plant-derived products in modern medicine with diminished adverse effects. Roadside plants in Tamilnadu also possess many such pharmacologically active compounds with therapeutical actions.