We developed a method of reducing the background fluorescence of samples made from formalin-fixed and paraffin-embedded blocks of the brain of the second-trimester human fetuses. For reducing excess background fluorescence, the samples were subjected to photobleaching using an LED lamp with blue and red emission peaks in the range of visible spectrum in a construction of an original design. The decrease in the background autofluorescence was checked by measuring the intensity of the emitted background fluorescence of the samples and relative abundance of immunopositive structures after immunohistochemical staining. It was found that the proposed method reliably reduced the background fluorescence of the samples, which improved the quality of multicolor immunofluorescence images of the cerebral cortex.