Poppy seed is a popular substance of many traditional Slovak cakes. We can eat quite great amount of it, sometimes more than 50 g. Existing problem in interpreting the results of opiate urine analysis in case of drug abuse arises from the natural occurrence of opiate alkaloids in poppy seed. Interpretation of morphine presence in urine sample is in some cases a problem because morphine present in the urine sample may come from different "sources". The presence of additional, respectively, other opiate in urine sample is significant help when interpreting the presence of morphine. We used poppy seed bought in supermarket for our experiment. Presence of morphine and codeine was determined in poppy seed extracts, whereas the concentration of majority opiate-morphine was 0.9 mg/100 g (9 ppm). This poppy seed was used for two series of experiment-poppy seed consummation, where four persons consumed 100g of poppy seed in the first series and 50 g in the second series. Urine samples were taken in regular 1h intervals where first urine sample was given for testing 3 h after consummation. Concentrations of total opiates were determined in each urine sample by screening examination. Morphine concentrations were determined in selected urine samples using GC/MS with internal standard.