Residual pleural thickening (RPT) develops in some patients after metapneumonic pleural effusion (MPE). Our aim was to identify factors that predict the development of RPT by retrospectively analyzing patients with MPE secondary to bacterial pneumonia in our practice from 1992 through April 1997. Patients were assigned to groups based on the presence or not of RPT (> 10 mm) three months or more after diagnosis of MPE. One hundred twenty-eight patients were included in the analysis. Seventy-nine patients (62%) developed RPT and 49 (38%) did not. Patients with RPT had significantly lower glucose levels and pH and higher LDH levels in pleural fluid. A higher percentage of patients with RPT had loculate pleural effusions and empyema, and they more often required insertion of drains. Logistic regression analysis showed that only glucose < 40 mg/dl (OR: 3.4; CI 95%: 2.3 to 4.5; p < 0.05) and the presence of pus collected from the initial thoracocentesis (OR: 3.6; CI 95%: 2.6 to 4.5; p < 0.01) were significantly associated with increased risk of developing residual pachypleuritis in subjects with MPE.