A quantitative analysis of morphine and codeine in human urine was performed after oral intake of cakes containing commercially available poppy seeds in order to estimate the possibility of positive doping results. Therefore, eight products from different manufacturers (poppy seeds or baking mixtures) and origin were obtained and analyzed by gas chromatography-mass spectrometry for the presence of the alkaloids. One selected batch of poppy seeds was used as an ingredient in a typical cake and was the object of an excretion study with nine volunteers. After application, several urine specimens contained morphine with concentrations higher than 1 microg/mL, and peak values of approximately 10.0 microg/mL were detected. Because the International Olympic Committee set a cutoff limit for morphine at 1 microg/mL, high-performance athletes could possibly test positive in doping control after consumption of products containing poppy seeds.