Data from two parallel household surveys conducted in Iraq by UNICEF in 1999 show that under-5 mortality declined steadily from 1974 to 1990, reaching about 63 per 1,000 live births in the period 1986-90. It then rose dramatically to 118 per 1,000 in 1991, the year of the Gulf War. The number of 'excess' under-5 deaths (i.e., the number in excess of the number predicted from past trends) in Iraq between 1991 and 1998 was calculated assuming that, instead of the rates measured by the 1999 survey for this period, either (a) average mortality rates for the period 1986-90 had been maintained, or (b) mortality had continued to decline at the rate observed between 1974 and 1990. According to these calculations, the estimated number of excess deaths resulting from the Gulf War and its aftermath up to 1998 was between 400,000 (assumption a) and 500,000 (assumption b).