This paper reports results acquired during the IUPAC Project No. 1999-021-1-400 Round Robin Test on the Molecular Characterization of Epoxy Resins by Liquid Chromatography. The results obtained by size exclusion chromatography (SEC) with column calibration are compared with those determined by SEC combined with a light scattering or a viscometric detector and absolute methods of molar mass determination. The influence of SEC experimental conditions on the obtained results is studied.