A GLC method for the specific identification and quantitation of iproiazid, a potent monamine oxidase inhibitor drug, is described. The free drug isolated from urine samples by two-phase extraction reinforced with salting out. Identification and quantitative determination at the microgram level are done on aliquots of the chloroform extract by GLC, using the 2-butyl analog as an internal standard. Iproniazid and potentially interfering compounds present in the extracts are also identified by GLC-mass spectrometry and TLC for supporting evidence of the GLC method's specificity.