This report describes the diagnostic contribution of gallium-67 scintigraphy in 145 cases of fever of unknown origin (FUO) at University Hospital in Leuven, Belgium, in 1980-1989. A final diagnosis was established in 99 (68%) of the 145 cases. Sixty-three scans (43%) were normal, and 82 (57%) were abnormal; only 42 of the abnormal scans (29% of the total number of scans) were considered helpful in diagnosis. Thus 49% of the abnormal scans were considered noncontributory to the diagnosis. In the same population, 15 (6%) of 266 ultrasonograms and 32 (14%) of 233 computed tomograms were helpful in diagnosis. We conclude that gallium scintigraphy remains a valuable screening tool in the investigation of FUO: it yielded diagnostic information in 29% of cases in which the probability of a definitive diagnosis was only 68%. We suggest the use of gallium scintigraphy as a second-step (as opposed to a last-resort) procedure in the evaluation of FUO.