At the end of the 1991 Gulf War the U.N. Security Council Resolution called upon IAEA, assisted by the U.N. Special Commission, to carry out inspections of all Iraqi nuclear installations. The IAEA Action Team succeeded in implementing, on very short notice, a comprehensive system of inspection activities, including sampling and analysis at the Agency's Laboratories and other laboratories in Member States. The Agency's Laboratories developed and implemented an analytical strategy with the aim to rapidly and accurately obtain the information necessary for verifying the Iraqi declarations. The analyses ranged from screening for - and /-emitters to accurate determinations of the amounts and isotopic composition of the radionuclides and associated trace elements and compounds. The arsenal of methods included ultra-sensitive radiometric methods, mass spectrometry, neutron activation, X-ray fluorescence and inductively coupled plasma emission spectrometry. Selected results include the detection of uranium chloride compounds, special composition steels, and quantitative accounting of uranium and plutonium production. The selectivity, sensitivity and reliability of the applied analytical techniques in conjunction with validated sampling procedures are essential components of an analytical measurements system that can provide credible results.