The combination of sulbactam (S) plus ampicillin (A) extends the activity of ampicillin (Amp) against beta-lactamase producing strains. This combination is therefore useful in many clinical situations including LRTI. A clinical trial was carried out to evaluate the clinical and bacteriological efficacy of S-Amp in LRTI in comparison with Amp alone. Concerning clinical outcome the results were satisfactory in 83.3% of cases for S-Amp group and 82.3% of cases for Amp group. Pathogen eradication was achieved in 87.5% and 70.5% of cases respectively for the S-Amp and Amp group.