Arbekacin (ABK) is one of aminoglycosides which has indications for septicemia and pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) in Japan. ABK shows good clinical and microbiological efficacies also against Gram-negative bacteria (GNB), including Pseudomonas aeruginosa. In addition, furthermore, ABK would be sometimes effective also against antimicrobial-resistant GNB. We investigated ABK inhalation, which showed good pulmonary drug delivery, for the treatment of pneumonia caused by multidrug-resistant Gram-negative organisms and MRSA. Six patients with pneumonia were treated with ABK inhalation therapy (50 mg x three times/day). We observed clinical effect for multidrug-resistant organisms in 6/6 patients. Although routine use of aerosolized antibiotics might not be able to be recommended for multidrug-resistant organisms, we might be able to adopt the ABK inhalation therapy for pneumonia especially caused by multidrug-resistant Gram-negative organisms in some situations where systemic therapy alone might be failure or inadequate, or where intravenous access is not available because of systemic toxicity. Further studies would be needed for ABK inhalation therapy for pneumonia.