Objective: Hospital readmission in patients admitted for community-acquired pneumonia (CAP) is frequent in the elderly and patients with multiple comorbidities, resulting in a clinical and economic burden. The aim of this study was to determine factors associated with 30-day readmission in patients with CAP. Design: A cross-sectional study. Setting: The study was conducted in patients admitted to 20 hospitals in seven Spanish regions during two influenza seasons (2013-2014 and 2014-2015). Participants: We included patients aged ≥65 years admitted through the emergency department with a diagnosis compatible with CAP. Patients who died during the initial hospitalisation and those hospitalised more than 30 days were excluded. Finally, 1756 CAP cases were included and of these, 200 (11.39%) were readmitted. Main outcome measures: 30-day readmission. Results: Factors associated with 30-day readmission were living with a person aged <15 years (adjusted OR (aOR) 2.10, 95% CI 1.01 to 4.41), >3 hospital visits during the 90 previous days (aOR 1.53, 95% CI 1.01 to 2.34), chronic respiratory failure (aOR 1.74, 95% CI 1.24 to 2.45), heart failure (aOR 1.69, 95% CI 1.21 to 2.35), chronic liver disease (aOR 2.27, 95% CI 1.20 to 4.31) and discharge to home with home healthcare (aOR 5.61, 95% CI 1.70 to 18.50). No associations were found with pneumococcal or seasonal influenza vaccination in any of the three previous seasons. Conclusions: This study shows that 11.39% of patients aged ≥65 years initially hospitalised for CAP were readmitted within 30 days after discharge. Rehospitalisation was associated with preventable and non-preventable factors