Two series of patients suffering purulent meningitis were treated: one (137 patients) with amoxycillin (200 mg/kg/day) by 4 intramuscular injections each day, the other with ceftriaxone (163 patients)/42 mg/Kg/day IM by intramuscular injections each day in the first 23 patients and then only one injection by day in the 140 other patients. Bacteriologically the superiority of CFTRX appears the whole studied strains: MIC of CFTRX are four times lower than those of AMOX for pneumococci, ten times lower for H. influenzae, hundred time lower for meningococci. Amongst the add strains the percentage of resistance to AMOX reaches 64 and only 7 to CFTRX. Pharmacologically, after a same dose of 50mg/kg the peak concentrations in CSF has the same level: CFTRX: 6.8 micrograms/ml, AMOX: 6 micrograms/ml. CSF levels remain efficient for 2 hours with AMOX and for 24 hours with CFTRX. The therapeutic index (mean antibiotic concentration in CSF/mean MIC of the strains) is higher with CFTRX than with AMOX (X 4 for pneumococci, X 15 for H. influenzae, X 100 for meningococci). Clinical results are better with CFTRX than with AMOX in each of the aetiological groups except meningococcal meningitis but the only significative difference concerns pneumococcal meningitis. Clinical tolerance of the two treatments was good. However 2 neonates treated with CFTRX has a severe eczematous erythrodermia and 8 other patients treated with CFTRX had diarrhoea due to elimination of the sensitive flora.