In 1998, we investigated a suspected outbreak of amebic liver abscesses caused by Entamoeba histolytica in the Republic of Georgia, using a case-control study. A questionnaire was administered and blood samples were obtained from cases and controls for serologic diagnosis. Medical records showed that E. histolytica infections were rarely diagnosed before 1998. However, from July through September 1998, 177 cases of suspected amebiasis were identified. Of 52 persons who had diagnosed liver abscesses, 37 (71%) were confirmed serologically to have antibodies against E. histolytica, compared with 11 of 53 persons (20.8%) diagnosed with intestinal amebiasis. In addition, 9-14% of asymptomatic controls were seropositive. Logistic regression identified the fact that interruptions in the water supply, decreases in water pressure, and increased water consumption were significantly associated with infection. The data support the hypothesis that drinking water was the source of infection, either because of inadequate municipal water treatment or contamination of municipal water in the distribution system.