Clinical studies on ceftriaxone (Ro 13-9904, CTRX) were carried out and the results were as follows: Twelve patients (acute purulent tonsillitis 1, pneumonia 6, urinary tract infection 5) were treated with CTRX, in doses of 21-48 mg/kg divided 2 times per day for 3.5-8 days intravenously. The overall efficacy rate was 100%. No adverse reactions were observed. No abnormal laboratory data were noted.