To investigate the efficacy and tolerability of treatment with a combination of levofloxacin and ceftazidime in Gram-negative hospital-acquired pneumonia (HAP) in the Intensive Care Unit (ICU), we performed a prospective, open-label, non-comparative, 1-year study in an Italian ICU. Patients received levofloxacin 500 mg twice a day intravenously plus ceftazidime 2 g three times a day intravenously for 7-14 days. Primary efficacy variables were clinical and microbiological responses at test-of-cure visit. Twenty-one patients were enrolled. Pseudomonas aeruginosa and Klebsiella pneumoniae were the most frequently identified pathogens. Clinical success was achieved in 17/21 clinically evaluable patients (81%) and in 12/15 microbiologically evaluable patients (80%). Regarding only the group with ventilator-associated pneumonia, cure was achieved in 10/14 clinically evaluable patients (71%) and in 11/14 microbiologically evaluable patients (79%). Therapy was well tolerated. We conclude that this combination regimen is safe and clinically and microbiologically efficacious in the treatment of Gram-negative HAP.