- A study of the path-integral method to compute the eigenvalues in two-dimensional waveguides is presented. The frequency-domain fields are computed by the path-integral method in the longitudinal and transverse directions in waveguides containing a delta-function source. The frequency-domain field is then Fourier transformed to determine its eigenvalue spectrum. Spectrum peak values are compared with the analytically calculated eigenvalues. Results are given for a parallel-plate waveguide and for a dielectric slab guide. 1997 John Wiley & Sons, Inc.