Results of a drug treatment program for control of amebic disease in an Amerindian reservation in northern Canada are reported. The population of approximately 350 was treated with metronidazole for a 12-month period. The drug was given in a single dose monthly for the first 3 months and bimonthly thereafter. Good results were achieved, with a 7-fold reduction from the 27 and 28 cases, respectively, seen during the two previous consecutive 12-month periods to only 4 cases during the 12 months of periodic treatments. A neighboring reservation, which served as a control, did not show a similar reduction in amebic disease over the same period of time. The drug was generally well tolerated except by infants and young toddlers, who showed a high incidence of vomiting. This improved when the dosage was reduced.