The resins of Boswellia species enjoy a wide array of traditional uses such as for treatment of skin diseases, as incense and fumigation for religious and cultural activities, and as an anti-inflammatory in medicine. rnThis dissertation focuses on the chemical investigation of resins obtained from two Boswellia species, namely, B. papyrifera and B. pirottae. The B. papyrifera resin obtained from Kebtele showed chemically distinct from the resin obtained from known B. papyrifera resin. From this resin, two diterpenes (104, 119), one fatty acid (186), two tirucallic acids (169 and 166), and seven boswellic acids (121,122, 123, 124, 132, 146, 147) were isolated. However, from known B. papyrifera, two diterpenes (111, 109) and one fatty acid (190) together with the same boswellic acids found in Kebtele resin were isolated. rnThe hitherto uninvestigated resin B. pirottae, an endemic species to Ethiopia, yielded eleven known triterpenes with different skeletons, three ursane (129, 130, 131), three oleanane (157, 149, 150), two lupane (148, 159) and three tirucallane (170, 200, 201) derivatives. rnHowever, in the remaining resins, B. sacra, B. frereana, B. neglecta and B. rivae, compounds that distingush one resin from the other have been isolated. rnIn this work, qualitative and quantitative analytical methods were developed using TLC, GC-MS, and HPTLC. The qualitative methods enabled the unequivocal identification of eight Boswellia species. The amount of the most potent anti-inflammatory and anti-cancer compounds found in the resin of B. papyrifera was compared with the well-known species, B. serrata and B. sacra. Accordingly, the amount of 11-keto-ï¢-boswellic acid (123) and 3ï¡-acetyl-11-keto-ï¢-boswellic acid (124) in the EtOH extract of B. papyrifera were determined as 14.0% and 8%, respectively. rnFrankincense resins are usually used as fumigants in cultural and religious ceremonies. We therefore analyzed the smokes of resins of B. papyrifera, B. sacra and B. serrata obtained by gentle burning and then capturing smoke constituents by extraction using solvents. Most of the compounds present in the resin were found in the smoke.