Self-quenching of the fluorescence mission of tetraphenylporphyrin at high concentrations in toluene at the ambient temperature (300K) is discussed in detail based on steady state and time-resolved fluorescence measurements. The fluorescence self-quenching is mainly attributed to re-absorption effect and the Förster type resonance energy transfer process (homotransfer). There-absorption effect is found to deform the fluorescence emission spectra significantly in energy positions as well as relative intensities of different peaks at high concentrations. Nearlyideal fluorescence emission spectra are observed at a concentration ~10⁻⁷ mol/L. Moreover, there is an apparent enhancement of the fluorescence life time value of tetraphenylporphyrinintoluene at high concentrations, especially on the blue side of the fluorescence emission spectra. To the best knowledge of the authors, this is the first detail report on the fluorescence self-quenching of porphyrinsin liquid medium. This finding carries great importance in view of the wide spread research on porphyrins in the fields of solar light harvesting, artificial photosynthesis, photodynamic therapy, etc.