The salivary excretion of cefoxitin (Mefoxin), a second-generation beta-lactam antibiotic of the cefalosporin group, which shows enhanced anti-anaerobic effect was investigated in oral surgery patients. In animal experiments the saliva levels of imipenem (Tienam) and meropenem (Meronem), which also belong to the betalactam carbapenem group were studied. The antibiotics were administered parenterally in single therapeutic doses, then blood samples were taken first after half an hour then hourly, and mixed saliva was collected for 6 hours. Cefoxitin was found to reach top level in the 1st hour, then this level decreased rapidly, and in the 4th hour it was no longer measurable. Out of the carbapenems imipenem showed highest level in the 2nd hour and in the 4th hour its concentration in the saliva was minimal. Meropenem reached a higher level in the saliva (1,5-2 times higher than the serum level) in the 2nd hour after administration, which persisted even in the 6th hour. The experimental results justify the administration of these antibiotics in dentistry and oral surgery.