Spectral holes were burned within the inhomogeneous (0,0) fluorescence excitation line of the T-0-->T-1 transition of 7H-benz[de]anthracen-7-ylidene in an n-hexane matrix at 1.7 K. The complicated spectrum of the obtained holes was interpreted with a model taking into account the zero-field splitting (ZFS) of both the triplet states contributing to the transition, the enforced planar symmetry of the carbene, and the domination of internal conversion in the relaxation of the excited T-1 state. Analysis of the hole-burning spectra produced the following ZFS parameters of the ground T-0 and excited T-1 slates: D-0 = (0.274 +/- 0.001) cm(-＇) + E-1, E-0 = (0.0292 +/- 0.0002) cm(-1) + E-1 and D-1 = (0.0168 +/- 0.0002) cm(-1) + E-1. The number of possible transitions between different spin sublevels is reduced as a consequence of the symmetry plane in the carbene and one of the ZFS parameters, we chose the smallest, E-1, cannot be estimated. The ZFS parameters of the T-0 state were also estimated by conventional matrix ESR and were in good agreement with the results of the hole burning experiments.