SummaryBetween October 1983 and October 1986, we looked for antibody to anti-delta in the sera of 218 patients, all carriers of the HBsAg who came to our hospital. Among the 52 patients of Italian nationality and resident in Italy, 9,4% had positive results for anti-delta. Among the HBsAg carriers resident in Belgium, 4 patients of Southern European origin, 1 African patient and 2 Belgian IV drug addicts had positive results for anti-delta.