Blastocystis hominis, other protozoans, and fecal leukocytes were tabulated on trichrome-stained fecal smears from 182 asymptomatic and 125 symptomatic control patients. No statistically significant difference in prevalence of B. hominis was found between the asymptomatic study group and the symptomatic control group; the clinical profile of subjects with B. hominis and those not infected was similar, and no correlation was found between the presence of B. hominis and that of fecal leukocytes. High concentrations of B. hominis were more frequent and more nonpathogenic protozoa were found in symptomatic patients than in those who were asymptomatic.