BACKGROUND: Hospital admissions for COPD exacerbations account for 70% of total costs of COPD treatment, and the duration of hospital stay is directly related to this cost. The aim of this study was to investigate possible associations of demographic, clinical, laboratory, and functional parameters with stay of subjects admitted for COPD exacerbations and to provide a score for the prediction of the need for prolonged hospitalization. METHODS: We included 164 consecutive subjects admitted to 2 respiratory medicine departments of 2 tertiary hospitals for a COPD exacerbation, and we evaluated laboratory, clinical, and functional parameters possibly related to the duration of hospital stay. RESULTS: Seven parameters evaluated on subject admission (Antonisen type of exacerbation, number of Exacerbations in the previous year, Charlson index of comorbidities, Oxygenation, Partial pressure of P aCO 2 in arterial blood gases, Dyspnea according to the Borg dyspnea scale, and history of chronic respiratory Failure) were able to predict stay and were included in a simple score named AECOPD-F. The area under the curve of the score for the prediction of prolonged hospital stay is 0.960, and a cutoff point > 3 predicts prolonged stay with a sensitivity of 84.5% and a specificity of 92.5% (95% CI 0.917-0.984). The AECOPD-F score was validated in a second group of 88 subjects admitted to the hospital for a COPD exacerbation. In the validation group, subjects with a score > 3 required prolonged stay compared with those with a score < 3 (8.0 [6.0 -10.0] vs 6.5 [4.0 -9.0] d, respectively, P ؍ .007). CONCLUSION: The AECOPD-F score could accurately predict stay in hospitalized COPD subjects. The implementation of this score in clinical practice could be useful in the discharge planning of such subjects.