The graduation thesis deals the stress state of composite wooden beams of three different cross sections and two simple static systems. By using Microsoft® Excel, a simple program for the analysis of composite wooden beams made of hardwood is created. The program can choose between the box, »I« and »T« cross-sections with arbitrary dimensions of flanges and webs. For the static system, simply supported beams of varying lengths can be chosen. The individual elements of the cross section are connected by mechanical fasteners (smooth nails of standard dimensions according to SIST EN 1995-1-1:2005) and may have different strength characteristics. By entering load, cross-section dimensions and length of the selected beam, the program calculates and draws a shear force and bending moment diagram. Based on the maximum values of moments and shear forces obtained, the program checks normal and shear stress as well as nails` carrying capacity and displacements of the beam. All calculations and processes of control are in accordance with the currently established standard for the design of timber structures, i.e. SIST EN 1995-1-1.