Plants often contain triterpenes that are difficult to analyse by high performance liquid chromatography (HPLC) due to lack of double bonds or other chromophores that can be readily detected spectrophotometrically. The present results show that light scattering mass detection (LS) is useful in such cases. We have been able to replace thin layer chromatography (TLC) with HPLC by using LS in evaluating triterpene contents in the bark resin of different birches (Betula pendula Roth., B. resinifera (Regel) Fern. & Raup., B. platyphylla Sucachev, B. ermanii Cham., B. papyrifera Marsh and B. pubescens Ehrh.). LS was five‐fold more sensitive than UV for papyriferic acid, which was used as a reference compound, and HPLC/LS revealed new compounds and qualitative relations that were undetectable by UV or TLC. This paper describes detection of a new major triterpenoid from B. pendula, the age dependency of the triterpenoid content in B. pendula and B. papyrifera and gives an interspecies comparison of the triterpenoid content of the different species.