Quantitative analysis of the scanning electrochemical microscope (SECM) experiments with heptode ultramicroelectrodes (UME) as a probe is performed by means of the boundary element method (BEM). The method is used to calculate the amperrometric steady-state response of the heptode UME in multiple electrode working mode, including the disk-ring competition mode, within the SECM feedback mode. SECM approach curves and line scans with the heptode UME are measured and analyzed by means of numerical simulations. Simulations are performed in the 3D space, thus enabling treatment of non-symmetrical systems, which the heptodes themselves and the line scan experiments are. The approach curves and the line scans are simulated using the real heptode geometry obtained from CCD camera images. The experimental parameters are determined and adjusted as a result of simulations. In particular, the focus was made on the analysis of such system imperfections as electrode/sample tilts, electrode scan heights and heterogeneous reaction rates at the UME. It is shown how the simulations featuring the real system geometry can be used further for the analysis of the SECM line scan and imaging experiments. (C) 2003 Published by Elsevier Ltd.