We have studied the mass distribution (N(M)) of branched poly(methyl methacrylate) (PMMA) formed by radical copolymerization of methyl methacrylate and ethylene glycol dimethacrylate by size exclusion chromatography (SEC). We show how the static structure factor of monodisperse branched PMMA can be obtained using a new type of on-line multiangle light scattering detector. We compare the monodisperse static structure factor with that of the polydisperse solutions and show that the polydisperse static structure factor can be derived from the monodisperse function using N(M) obtained from SEC. Both the static structure factor and the mass distribution are found to be consistent with predictions from percolation theory. Using an on-line viscometer we have determined the molar mass dependence of the intrinsic viscosity.