A method for the determination and quantification of higher-functional epoxides in liquid diglycidylether of bisphenol-h (DGEBA)-based epoxy resins, and for the determination and quantification of the amount of branching in solid DGEBA-based epoxy resins by C-13 n.m.r. is described. Model compounds were synthesised and their chemical shifts assigned. Examples for both types of resin are given, and the usefulness of the method is shown by the example of a production campaign of a solid resin. The increase of branching and the build up of molecular weight are compared and discussed.