Abstract: Homotopy principles are used in computer simulation of magnetic resonance spectra. Multidimensional homotopy provides an efficient method for accurately tracing energy levels, and hence transitions, in the presence of energy level anticrossings and looping transitions. The application describes the implementation of homotopy to the analysis of continuous wave electron paramagnetic resonance spectra. The method can also be applied to electron nuclear double resonance, electron spin echo envelope modulation, solid state nuclear magnetic resonance and nuclear quadrupole resonance spectra.