The objective — of the present study was to elucidate the specific features of the distribution of neohistamine methylsulfate (proserin) in the organism of the omnivorous warm blooded animals following its intragastric administration. The analytical methods included TLC, HPLC, and UV-spectrophotometry. Neohistamine methylsulfate was administered intrgastrically to the male Wistar rats at a dose equivalent to the triple LD50 dose. The substance of interest was extracted by acetone from the biological matrices of the dead animals and purified by sequential treatment with the relevant solvents and chromatography in a thin layer of the reverse-phase sorbent (C14—C15 bonded phase model) with the elution in the buffer solution (pH 1.98) — acetone (8:2) system. The compound of interest was identified based on the Rf values (obtained by TLC), retention time (in HPLC), and the spectral characteristics. The quantitative determination of the analyte in the biomatrices was performed with the use of UV spectrophotometry. The analytical methods were validated based on the criteria for linearity, selectivity, correctness, and precision as well as detection threshold and results of quantitation. The largest amount of the study compound were determined in the heart (365.2±33.94 mcg/g), spleen (288.6±24.97 mcg/g), kidney (127.6±9.33 mcg/g), and the gastric walls (124.6±12.17 mcg/g) of the experimental animals.