Liquid furane and thiophene are decomposed by γ-rays with total G-values of 7.0 and 3.2, respectively. The main products are polymers which have the initial elementary composition, olefinic double bonds and CO-groups (in furane). Gaseous products such as hydrogen, acetylene, propylene and carbon monoxide are formed with 100 eV yields below unity. The results are compared with the known radiolysis of liquid benzene.