Seventeen patients with mycoplasmal pneumonia were administered intravenous minocycline, a tetracycline antibiotic with long-acting effects. Excellent therapeutic effects were observed both clinically and bacteriologically. The organism was eliminated in a shorter period of time compared to other antibiotics used for the treatment ofMycoplasma pneumoniae infections. Aside from 1 patient who experienced nausea and vomiting and was taken off minocycline, no other adverse effects were noted in these patients. Minocycline should be strongly considered as therapy for mycoplasmal pneumonia because it may completely eradicate the organism within 7 days.