Structure Function Measurements at HERA and Perturbative QCD

New results from the H1 and ZEUS collaborations on the measurement of cross-sections at very high Q (up to 25000 GeV) and on the proton structure function F2(x,Q ) for momentum transfers squared Q ≥ 1.5 GeV and Bjorken x ≥ 3.5·10 are reported, using data collected at HERA mainly in 1994. No deviations from the Standard Model have been observed at high Q and F2 is seen to increase significantly with decreasing x, even in the lowest reachable Q region. Comparisons at low Q with fixed target experiments and with models based on pomeron exchange are presented. The F2 results are well described by a Next to Leading Order QCD fit, and are consistent at the present level of precision with the rise at low x within this Q range generated via the DGLAP evolution equations. The gluon density is extracted and being observed to rise at low x.