Monoterpenes, are the largest class of plant secondary metabolites. The review discusses some of their key roles in chemical ecology. Several applications of monoterpenes in flavour and fragrance industry, bioremediation, in prevention and therapy of several inflammatory infection, potential disease-preventive phytochemicals, especially for cancer development, are presented. This review also aims at a potential offered by biocatalysis for the synthesis of valuable natural monoterpenes, highlighting relevant biotransformation of suitable precursors (like pinene, limonene, myrcene) using microorganism and porphyrins. The industrial processes based on biotechnological methods are also discussed in terms of their advantages over classical chemical synthesis and extraction from natural sources.