Pristinamycin, an antimicrobial agent classified among synergistines is composed by two components : I streptogramin A and streptogramin B. These two components are tested simultaneously with the same plate during the antibiogram which complicates the detection of some phenotypes of streptogramin resistance. In order to prevent this difficulty we have determined in gelosis medium the Minimal Inhibiting Concentration (MIG) of each component A and B and of their association against 166 S. aureus strains and 31 S. epidermidis strains which phenotype of MLS resistance have been determined. A higher frequency of phenotype of MLS resistance has been observed in strains resistant to meticillin. The strain resistant to pristinamycin belonged to LSA phenotype (3 % of S. aureus) and to MLS(B) + S-A phenotype (1,2 % of S. aureus). Our strength of S. epidermidis strains is insufficient to take conclusion about the pristinamycin resistance.