The diagnostic value of ultrasonic (US) examinations followed by US-guided needle biopsy in the differential diagnosis of peripheral pulmonary infiltrates is demonstrated examining two patients with AIDS-related pulmonary infiltrates. Ultraso-guided needle biopsy was performed after thoracic radiograph, computed tomography, and bronchoscopy could not confirm a diagnosis. Biopsy specimens obtained via US-guided needle biopsy revealed local Pneumocystis carinii (case 1) and chronic Aspergillus pneumonia (case 2).