Frankincense can be obtained from various species of the genus Boswellia and, interestingly, it has been employed for medicinal, religious, and sacrificial purposes for over 5000 years. There are a number of triterpenes, such as ursanes and oleanane-type triterpenes, which are the major natural products of the resin of frankincense. Since the first isolation of β-Boswellic acid (BA) from Boswellia in 1898, the isolation and structural assignment of other BA derivatives and other terpenoids has continued. A large scale of these naturally isolated derivatives was prepared via partial synthesis, which allowed creation of a library of BA derivatives. The synthetic modifications have taken place mostly on rings A and C of the pentacyclic terpene skeleton. Based on potent anticancer and antiinflammatory effects of natural BAs, interesting chemical diversity has been generated on BA scaffolds via ring A modification at the C3-OH and C24-CO2H moieties. Interestingly, these semisynthetic BAs possess potent anticancer and antiinflammatory activities towards various cancer cells and a SAR study showed that an amino group and some heterocyclic rings attached to ring A possess better activity. Detailed mechanisms of action were performed on some BA derivatives. Moreover, a few fascinating cembrene derivatives have been isolated from Boswellia species. Among these are the incensole and incensole acetate, which were synthetically modified and tested for antidepression activities. There are seven reported total syntheses of incensole and incensole derivatives.