The work presents the theoretical basis of Additional Finite Element Me-thod (AFEM), which is a variant of the Finite Element Method (FEM) for analy-sis of reinforced concrete structures at limit state. AFEM adds to the traditional sequence of problem by FEM the units of the two well-known methods of the structural design: method of additional loads and limit state method. The prob-lem is solved by introduction of ideal failure models and additional design dia-grams formed from additional finite elements, where each AFE describes the limit state reached by the main element. The main relations defining the proper-ties of AFEs as well as the examples of the use of Additional Finite Element Me-thod for analysis of reinforced concrete structures at limit state are given in the work too.