To identify characteristics of day care facilities associated with H. influenzae disease, we compared 92 licensed facilities in which a case of H. influenzae disease had occurred with randomly selected facilities at which no cases occurred. Matched univariate analysis showed that personnel at facilities where H. influenzae disease occurred were more likely than those at control facilities to use towels or handkerchiefs to wipe children's noses, admit children who were not toilet trained or had diarrhea ("liberal fecal policy"), had a narrower age range, were more likely than control facilities to be for-profit and less likely to use volunteers. In a multivariate model that adjusted for age range, profit status and liberal fecal policy, towel or handkerchief use (OR 5.5, 95% CI: 1.1, 30) was the only variable independently associated with case facilities. This is the first association of a specific day care practice with H. influenzae disease.