MICs were performed on 62 streptococci isolated from the blood of neutropenic patients from 1986 to 1992 using the NCCLS broth microdilution procedure. Species isolated were 43 S. mitis, 6 S.pneumoniae, 5 S.sanguis, 1 S.pyogenes, 1 beta-hemolytic streptococcus of the group G, 1 S.adjacens, 1 S.intermedius, 4 not identified isolates (2 alpha-hemolytic, 1 non-hemolytic and 1 nutritionally variant strains). 26% of all strains were resistant or intermediate to penicillin (MIC 90: 2 mg/l) and 89% to norfloxacine (MIC 90: 32 mg/l). All were susceptible to vancomycin. Among cephalosporins, all strains were susceptible to cefotaxime (MIC 90: 1 mg/l), ceftriaxone (MIC 90: 1 mg/l) and cefepime (MIC 90: 2 mg/l) while 19% were R or I to ceftazidime (MIC 90: 16 mg/l). All were susceptible to imipenem (MIC 90: 0.5 mg/l) and meropenem (MIC 90: 1 mg/l). Among the third generation cephalosporins, ceftazidime--the agent of this class of antibiotics that is most often used for the empirical therapy of febrile episodes in neutropenic patients (in combination but also in monotherapy)--has a high resistance rate as compared to the other compounds.