Total Hadronic Cross-Section of Photon-Photon Interactions at LEP              
  
 The total hadronic cross-section for the interaction of real photons,         
 is measured for Photon-Photon centre-of-mass energies of                      
 10 < W < 110 GeV. The Photon-Photon cross-section is extracted from a         
 measurement of the process                                                    
        e+e- --> e+e- Gamma^* Gamma^* --> e+e- + Hadrons                       
 using a luminosity function for the photon flux and form factors for          
 extrapolating to real photons (Q^2=0). The data were taken with the           
 OPAL detector at LEP at e+e- centre-of-mass energies of 161 to 183 GeV.       
 The cross-section is compared with Regge factorisation and with the           
 energy dependence observed in Photon-Proton and Proton-Proton                 
 interactions. The data are also compared to models which predict a            
 faster rise of the total hadronic cross-section due to additional hard        
 Photon-Photon interactions not present in hadronic collisions.                
  
 Parallel session :2                   
 Plenary  session :12