A total of 161 patients with lobar or segmental consolidation were examined by realtime ultrasound and Doppler ultrasound. Air bronchograms were detected in 141 patients, fluid bronchograms in 27 patients, and parapneumonic effusion in 74 patients. In 36 patients with necrotizing pneumonia, ultrasound detected microabscesses in 33 (91.7%) compared with the air-fluid levels detected by standard chest radiographs in 20 patients (55.6%; p less than 0.05). Of 31 patients with tumors causing obstructive pneumonitis, 29 (93.5%) had tumors detected by chest ultrasound, whereas only 11 patients (35.5%) had chest radiographs that suggested a tumor was causing the obstructive pneumonitis (p less than 0.05). Chest ultrasound was used to guide thoracentesis for parapneumonic effusion in 65 patients, with a 100% success rate. Twenty-six patients with necrotizing pneumonia underwent ultrasound-guided needle aspiration of microabscesses. The procedure was successful in 24 patients (92.3%), and 21 patients (80.8%) had microbiologic confirmation. Twenty patients with tumor-associated obstructive pneumonitis received needle aspiration biopsy under ultrasound guidance; 19 patients (95.0%) had the histology confirmed. Five patients with malignancy manifesting as pulmonary consolidation underwent a diagnostic ultrasound-guided needle aspiration biopsy. Five patients (3.8%) developed complications of minimal pneumothorax or mild hemoptysis in 132 episodes of needle aspiration. We conclude that ultrasonography is useful for the evaluation of pulmonary consolidation. It can also be used for needle aspiration guidance for etiologic diagnosis of patients with complicated pneumonia.