The carriage rate of ampicillin-resistant Hemophilus influenzae type B in a chronic care facility was investigated. Up to 48% of the children carried this strain. Of interest was the finding of simulaneous carriage of ampicillin-resistant and ampicillin-sensitive HITB, a phenomenon which was detected by using both chocolate agar and chocolate agar containing 2 microgram/ml of ampicillin. A trial of sulfamethoxazole-trimethoprin successfully eradicated the ampicillin-sensitive HITB, but had no effect on the ampicillin-resistant HITB.