Background: Pneumonia is a frequently observed complication following esophagectomy. The lack of a uniform definition of pneumonia leads to large variations of pneumonia rates in literature. This study was designed to develop a scoring system for diagnosing pneumonia following esophagectomy at the hospital ward. Methods: In a prospective cohort study of esophagectomy patients, known risk factors for pneumonia, temperature, leukocyte count, pulmonary radiography and sputum culture added were evaluated. Primary outcome was defined as the decision to treat suspected pneumonia. Multivariate Cox regression analysis with backward selection was used to identify predictors of pneumonia treatment. Results: The majority of postoperative pneumonia treatments (88.2%) occurred at the hospital ward, where treatment was observed in 67 (36.2%) of 185 patients. Independent diagnostic determinants for pneumonia treatment were temperature (hazard ratio (HR) = 1.283, p = 0.073), leukocyte count (HR = 1.040, p = 0.078) and pulmonary radiography (HR >11.0, p = 0.000). Sputum culture did not influence the decision to treat pneumonia. These findings were used to develop a scoring system which includes temperature, leukocyte count and pulmonary radiography. Conclusion: The decision to treat pneumonia is based on temperature, leukocyte count and pulmonary radiography findings. The proposed clinical scoring system for pneumonia following esophagectomy at the hospital ward has the potential to aid clinical practice and improve comparability of future research in esophageal cancer surgery.