Abstract: The fluorescence quenching of anthracene and pyrene by 1,3-bis-(N-phenyl-N-methylamino)propane (DMA-AMD), N-methyl-N-ethylaniline (MEA) and dimethylani-line (DMA) in n-pentane, methylcyclohexane and n-hexadecane was investigated. The quenching was accompanied by the formation of the corresponding exciplex. The bichromophoric DMA-AMD was found to be a more efficient quencher than either MEA or DMA, yet it yields an exciplex with lower fluorescence efficiency. The result may be accounted for by the intramolecular quenching of the exciplex by the second anilino group in DMA-AMD. The bimolecular quenching constants by these anilines depend on the solvent viscosity and may exceed theoretical diffusion controlled limit in viscous hydrocarbons.