Mastic (Pistacia lentiscus) is an evergreen shrub or small tree growing to 3-4 m tall, native to the Mediterranean region from Morocco and Iberia east to Turkey.

A hard, brittle, transparent resin, also known as mastic, is obtained from the tree. The resin is collected by bleeding from small cuts made in the bark.

Mastic flavouring is used for liquors (masticha alcoholic drink) and chewing gum pastiles among other uses. It was the Sultan's privilege to chew mastic, and it was considered to have healing properties.

The best qualities grow in the Greek island of Chios in the Aegean Sea. People in the Mediterranean region have used mastic as a medicine for gastrointestinal ailments for several thousand years. The first century Greek physician and botanist Dioscorides wrote about the medicinal properties of mastic in his classic treatise De Materia Medica ("About Medical Substances").

In recent years, university researchers have provided the scientific evidence for the medicinal properties of mastic. A 1985 study by the University of Thessaloniki discovered that mastic can reduce bacterial plaque in the mouth by 41.5 percent. A 1998 study by the University of Athens found that mastic oil has antibacterial and anti-fungal properties. Another 1998 Nottingham University study published in the New England Journal of Medicine found that mastic can heal pectic ulcers.