Acinetobacter organisms, which are a common cause of ventilator-associated pneumonia (VAP) in some health care centers, are becoming more resistant to such first-line agents as imipenem-cilastatin (Imi-Cil). Sulbactam has good in vitro activity against Acinetobacter organisms; thus, ampicillin-sulbactam (Amp-Sulb) may be a viable treatment alternative. The outcomes for critically ill trauma patients with Acinetobacter VAP treated with either Amp-Sulb or Imi-Cil were compared retrospectively. A total of 77 episodes in 75 patients were studied. Fourteen patients were treated with Amp-Sulb, and 63 patients were treated with Imi-Cil. Treatment efficacy was similar in the Amp-Sulb and Imi-Cil groups (93% vs. 83%, respectively; P > .05). No statistically significant differences between groups were noted with regard to associated mortality, duration of mechanical ventilation, or length of stay in the intensive care unit or hospital. However, adjunctive aminoglycoside therapy was used more often in the Amp-Sulb group. Patients generally received Amp-Sulb because of imipenem resistance. Amp-Sulb was effective in treating a small number of patients with Acinetobacter VAP; however, more data are needed.