Abstract The diagnostic criteria of aspiration pneumonia have not been established, and it remains an underdiagnosed entity. Diagnosis and cause investigation is essential in improving the management of aspiration pneumonia. The Japanese Respiratory Society Guidelines for the Management of Pneumonia in Adults (JRS Guidelines) show a list of risk factors for aspiration pneumonia. We developed an algorithm to aid physicians in evaluating these possible underlying factors and guide their management with a focus on aspiration pneumonia. The algorithm was developed based on the JRS Guidelines. The algorithm suggested dysphagia screening, pneumococcal and influenza vaccination, and other preventative measures for pneumonia. The algorithm was implemented in the acute setting of a general hospital among older patients admitted with pneumonia. Their outcomes were compared with a historical control group constituting similar patients from the previous year. Forty patients with pneumonia were assessed with the algorithm group, and 44 patients were included in the control group. In the algorithm group, significantly more cases (95.0% vs. 15.9%, p