The spectral-luminescent and other properties of substances depend substantially on the symmetry of a molecule. Consideration of the problem of the symmetry effect of a luminophor molecule on the fluorescence parameters and, in particular, on the intercombination conversion constant requires a systematic analysis of the considerable experimental material. The author has studied and analyzed the spectral-luminescent properties of 22 specially selected substances structurally similar in pairs but distinct in symmetry: 9-methylanthracene, 9,l0-dimethylanthracene, 9-chloroanthracene, 9,10-dichloroanthracene, 9-phenylanthracene, 9, l0-diphenylanthracene, 2,2'-methylene-p-terphenyl, 2,2'-methylene-5',6"-methylene-p-terphenyl, 3-phenyldibenzofuran, benzo (1,2-B:4,5-B')-bisbenzofuran, PPO, PPD, PNPD, PNND, PBD, BBD, trans-l-(4-biphenylene)-2-phenylethylene, diphenyl stilbene, 4-methoxybiphenyl, 4,4'-dimethoxybiphenyl, N,N-dimethylaniline and N,N,N',N'-tetramethyl-p-phenylenediamine. Since molecule coplanarity exerts a considerable influence on the fluorescence parameters, the substances are selected in such a way that when passing from an odd molecule to an even (more symmetrical) one, their coplanarity degree does not vary or varies only slightly. The UV spectra of the substances were measured using a SPECORD UV-VIS spectrofluorimeter. The author selected cyclohexane as the solvent, having good dissolving ability and exerting a minimal effect on the substance under study. The fluorescence spectra of solutions of the investigated substances were measured on a Hitachi MPF4 spectrofluorimeter.