An HPLC method for the separation of boswellic acids, the active constituents in Boswellia serrata resin has been developed. The first accurate determination of 6 individual acids was possible in the resin as well as in multi-component preparations. By using an acidic mobile phase, raised temperature and a 4 microm Synergi MAX-RP 80 A column the acids could be detected at levels as low as 0.9 microg/ml. The study of market products revealed significant variations in the content of these pharmacologically active compounds in commercial samples.