Résumé : The hadronic photon structure function F 2 γ has been measured in the Q 2 range from 4 to 30 GeV2/c 4 and down to x values of order 0.001, using data taken with the DELPHI detector at LEP between 1991 and 1993. A comparison is made with several F 2 γ parameterizations with special emphasis on their low x behaviour. A result on the Q 2 evolution of F 2 γ is presented. © 1996 Springer-Verlag.