Chemical pleurodesis is performed in pneumothorax patients to treat nonresolving air leakage or prevent recurrence. However, factors that might predict the need for chemical pleurodesis remain unknown. Therefore, this study investigated predictive factors for the application of chemical pleurodesis for pneumothorax. We retrospectively analyzed 401 adult pneumothorax patients who underwent chest tube drain insertion during hospitalization at Fukujuji Hospital from January 2016 to December 2020. The patients were divided into 3 groups: the pleurodesis group, comprising 89 patients treated with chemical pleurodesis; the nonpleurodesis group, comprising 206 patients treated without chemical pleurodesis; and the surgical group, comprising 106 patients treated surgically. Data for patients in the pleurodesis group were compared to those in the nonpleurodesis or surgical group, and a predictive score of the application of chemical pleurodesis for pneumothorax was developed. Compared with the nonpleurodesis group, in the pleurodesis group, patient age was higher (P