This study aimed to optimize a method for determining N-ethyldiethanolamine (EDEA) and N-methyldiethanolamine (MDEA) in urine samples using gas chromatography-mass spectrometry. The analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and the most proper organic solvent was investigated. Best recoveries were found for acetonitrile and dimethylsulphoxide. The recoveries of spiked samples (100 ng ml(-1)) were found as 108 +/- 5.7% for EDEA and 97 +/- 6.4 for MDEA. The limit of detection (LOD, S/N = 3) values were 0.5 ng ml(-1) and 0.4 ng ml(-1) for EDEA and MDEA, respectively. The precision of the method in terms of RSD was between 5-8%.