AbstractFive fossil resins from various localities in the Czech Republic were investigated. To arrive at more detailed description of the resins, pyrolysis-gas chromatography/mass spectrometry with derivatisation using tetramethylammonium hydroxide, gas chromatography-mass spectrometry, and micropetrography were applied. The content of organic macerals, composition of biomarkers in the solvent extracts and in the pyrolysates have been determined and compared to amber samples. The analyses clearly indicate that all resins belong to the Class Ib type derived from regular labdane structures that lacked succinic acid. The presence of labdane type diterpenoids and the absence of plant triterpenoids in the resin point to a conifer (gymnosperm) source which contrasts with the angiosperm source of Sarawak amber from Malaysia. According to their chemical composition, all Czech resins can be assigned to the Cupressaceae family. There was an obvious difference between a Duxite sample (Miocene) and other resins that could be attributed to deposition inside wood, which did not allow degradation of the resin.