Biofuels including ethanol and biodiesel represent an important renewable fuel alternative to petroleum-derived transport fuels. Materials compatibility is a major concern whenever the fuel composition is changed in a fuel system.The aim of this work is to study the interaction between elastomers such as FKM EPDM CR CSM NBR IIR VMQ and FVMQ and biofuels such as biodiesel E85 (fuel with 85% ethanol) and B10 (heating oil with 10% biodiesel). Experiments were conducted with tests specimens of these elastomers at 40°C and 70°C for 84 days to document the changes in the mass volume and tensile properties of these sealing materials according to ISO 1817.The exposure tests in E85 showed that the weight gain caused by swelling was in the range up to 12%. The lowest decrease in the tensile properties was determined for FKM EPDM und IIR which were evaluated as resistant to E85.Biodiesel absorbed water more quickly and aged faster than conventional diesel fuel. The weight loss of the elastomers varied between 9% (FKM) and 126% (CSM) in biodiesel. FKM was evaluated as resistant while NBR EPDM CSM CR IIR FVMQ and VMQ were evaluated as not resistant in biodiesel.The fluorine-containing elastomers FKM and FVMQ absorbed much less B10 and swelled less. NBR EPDM CR CSM IIR and VMQ were not resistant to B10 at all as the decrease in the tensile properties was significantly over 50%.Among all of the elastomers FKM showed high compatibility with biodiesel E85 and B10 up to 70°C.