Gum resin extracts of Boswellia species have been traditionally applied in folk medicine forcenturies to treat various chronic inflammatory diseases, and experimental data from animal models andstudies with human subjects confirmed the potential of B. spec extracts for the treatment of not onlyinflammation but also of cancer. Analysis of the ingredients of these extracts revealed that the pentacyclictriterpenes boswellic acids (BAs) possess biological activities and appear to be responsible for the respectivepharmacological actions. Approaches in order to elucidate the molecular mechanisms underlying thebiological effects of BAs identified 5-lipoxygenase, human leukocyte elastase, toposiomerase I and II, as wellas IκB kinases as molecular targets of BAs. Moreover, it was shown that depending on the cell type and thestructure of the BAs, the compounds differentially interfere with signal transduction pathways including Ca2+-and MAPK signaling in various blood cells, related to functional cellular processes important forinflammatory reactions and tumor growth. This review summarizes the biological actions of BAs on thecellular and molecular level and attempts to put the data into perspective of the beneficial effects manifested inanimal studies and trials with human subjects related to inflammation and cancer.