We describe a change in epidemiology of 3,615 cases of malaria in a rural area in Ethiopia (from September 11, 1998, through September 10, 2003). The Plasmodium falciparum infection increased from 40.9% in the first year to 73.4% in the last year, and the Plasmodium vivax infection decreased from 54.7% to 22.4% (p < .001).