A gas chromatographic-mass spectrometric screening procedure for the detection of the following alkanolamine antihistamines and their metabolites in urine after acid hydrolysis and acetylation is described: bencyclane, carbinoxamine, chlorbenzoxamine, chlorphenoxamine, clemastine, diphenhydramine, diphenylpyraline, doxylamine, mecloxamine, medrylamine, orphenadrine and phenyltoloxamine. The acetylated extract was analysed by computerized gas chromatography-mass spectrometry. An on-line computer allows rapid detection using ion chromatography with the ions m/z 58, 139, 165, 167, 179, 182, 218 and 260. The identity of positive signals in the reconstructed ion chromatograms was confirmed by a comparison of the stored full mass spectra with the reference spectra. Possible interferences with related compounds that yield the same hydrolysis products or metabolites are discussed. The ion chromatograms, reference mass spectra and gas chromatographic retention indices (OV-101) are documented. The procedure presented is integrated in a general screening procedure (general unknown analysis) for several groups of drugs.