Thirty patients, without any valve defect, cardiac malformation or previous antibiotic administration and presenting dental infections, have been treated either with amoxycillin-clavulanic acid or amoxycillin and metronidazole. Aerobic and anaerobic bacteria have been isolated. These infections were due to mixed flora. Nearly one half of anaerobes were Peptostreptococcus, S. milleri and S. sanguis being predominant among aerobes. The species identified were those found in the mouth in the absence of infection becoming as opportunistic flora. The percentage of cures was equivalent in the two groups. the association amoxycillin-clavulanic acid seems to be as active as amoxycillin + metronidazole on the microflora isolated from dentogenous pyogenic infections.