Monoterpenes, the major components of essential oils, belong to the group of isoprenoids containing ten carbon atoms. Being widely distributed in the plant kingdom they are extensively used in cuisine and human health care products. Studies have shown that both natural monoterpenes and their synthetic derivatives are endowed with various pharmacological properties including antifungal, antibacterial, antioxidant, anticancer, antiarrhythmic, anti-aggregating, local anesthetic, antinociceptive, anti-inflammatory, antihistaminic and anti-spasmodic activities. Monoterpenes act also as regulators of growth, heat, transpiration, tumor inhibitors, inhibitors of oxidative phosphorylation, insect repellants, feline and canine attractants and antidiabetics. These interesting activities which might be potentially used not only in pharmaceutical, but also food and cosmetic industries are discussed below.