Résumé : The rate of bactericidal activity of a new cephalosporin, cefpiramide, was compared with amoxicillin and cefotaxime for ten strains of Streptococcus faecalis. Cefpiramide was bacteriostatic at 10 μg/ml and bactericidal at 100 μg/ml. Cefotaxime only reduced the growth rate. A paradoxical effect was observed in all ten strains tested against amoxicillin.