Transient triplet electron paramagnetic resonance (EPR) spectra of dibenzocycloheptadienylidene (DBC) and substituted diphenylmethylenes were observed in a rigid glassy matrix at low temperatures. On excitation with the wavelength of the T-T transition of DBC, polarized EPR spectra due to the both ground (T-0) and excited (T-1) states were observed at a short delay time (180 ns) after the laser pulse. The T-1 components in the spectrum decayed faster than the other and diminished at I mus after the laser pulse irradiation. The remaining signals after the decay of the T-1 state were unambiguously assigned to the T-0 state, taking into account the steady-state (SS) EPR results. From analysis of the spectrum of the short-lived triplet species, the zero-field splitting (ZFS) parameters, \D\ = 0.201 and \E\ = 0.008 cm(-1), were determined for the T-1 state directly. The parameters obtained were comparable to those of the T-1 state of diphenylmethylene (DPM). The polarization patterns of the transient spectra match well with interpretation as anisotropic intersystem crossing induced by the spin-orbit couplings between the S-n and the triplet states. On the basis of the results of magnetophoto-selection experiments, we also confirmed that the principal axes in the T-0 and T-1 states did not differ significantly from each other. The behavior of the methyl-substituted DPM resembles that of DPM and DBC, indicating that the methyl group does not affect the photophysical and photochemical properties of the T-0 and T-1 states. Although the SS EPR spectra were observed for the To state of substituted DPM derivatives, the chemical properties of the excited states were affected by substitution of electron-donating (OCH3) or -withdrawing (CN) groups.