Background/Aim. Heroin is diacetylated morphine. Its ability to induce euphoria has led to its frequent abuse, giving rise to psychological and physical dependence. It has a short half-life, of approximately 2−6 min. In the brain, heroin undergoes deacetylation to 6-monoacetylmorphine (6−MAM) and morphine. Detection of 6-acetylmorphine in the urine is indicative of heroin use. The aim of this study was to compare sensitivity and reliability of two analytical methods, a multicolumn liquid chromatography system with UV scanning detector (HPLCUV) and liquid chromatography-mass spectrometry detection (LC-MS) in opiate determining in post mortem material. Methods. Post mortem samples (blood, urine and vitreous humor) were analyzed by liquid chromatography with UV and MS detection. The samples were prepared by liquid-liquid extraction with mixture chloroform-isopropanol (9:1). Separation was performed on C8 column with mobile phase composed of 55% acetonitrile-glacial acetic acid (99:1) and 45% 20 mM ammonium acetate. Results. The analysis of blood samples, urine, and eye liquid by the use of multicolumn HPLC-UV method confirmed the presence of morphine in the samples of blood and urine, codeine only in urine, and 6-MAM in the samples of urine and eye liquid. Using LC-MS method morphine was confirmed in all of the samples, while codeine was confirmed in urine and in the sample of eye liquid. In the samples of eye liquid and urine 6-MAM was confirmed. Conclusion. For determination of opiates in post mortem material LC-MS technique is more sensitive and reliable as compared to multicolumn liquid chromatography.