Sir .—The current interest in the literature 1-4 in the spread of Haemophilus type b infections prompted us to add our recent experience with this problem that tends to confirm previous observations. Three infants, ages of 10 and 17 months, were admitted within an eight-day period with serious Haemophilus influenzae type b infections, two with bacterial meningitis and one with cellulitis of the cheek (cases 1, 2, 3, Table). The three infants were among five children younger than 2 years of age cared for during the day, as a group, in a small apartment by one grandmother babysitter. This striking coincidence of disease prompted an epidemiological investigation of immediate contacts including history, physical examination, nasopharyngeal cultures, and paired serum determinations for capsular antibody titers by radioimmunoassay technique. A total of 17 individuals were studied. The positive findings are shown in the accompanying Table. It was noted that one of the