Ninety-four isolates of Yersinia pestis collected by the French army between 1964 and 1988 were evaluated for their susceptibilities to 24 antibiotics by the agar dilution method. All the isolates were susceptible to beta-lactam antibiotics including imipenem, to fluoroquinolones, aminoglycosides and to doxycycline. The most active compounds were fluoroquinolone antibiotics, third-generation cephalosporins and aminoglycosides.