|Abstract||During summer 1991 an outbreak of louse-borne relapsing fever occurred simultaneously in two transit camps established for prisoners of war being returned from Eritrea at the end of the Ethiopian civil war. Only antibiotic treatment was given at the Bahr Dar camp where the frequency of cases increased for 20 days. Vector control by delousing in addition to antibiotics was given at Mekele camp where the frequency of cases fell over a similar period. This difference was significant (p < 0.001). Furthermore, there was a significant correlation between the decreasing proportion of camp inhabitants that had not been deloused at Mekele camp each day and the numbers of patients with fever (r = 0.89, p < 0.001). Taken together, these results confirm that effective control of an epidemic of louse-borne relapsing fever is dependent on efficient vector control in addition to antibiotic treatment.