Lung biopsy, performed as a diagnostic procedure in children with pulmonary disease to guide treatment, may not provide a diagnosis or change therapy. We therefore reviewed our experience with the procedure to determine its use. We reviewed all children undergoing lung biopsy at two large children's hospitals, 2001 to 2010. Lesions were categorized as either diffuse or localized based on final radiological interpretations. Pathological interpretations and subsequent treatment regimens were reviewed for specificity of diagnoses and any changes in therapy. Of 99 patients, there were 14 diffuse and 85 localized pulmonary lesions. Biopsy confirmed the radiological diagnosis in 29 (29%), 71 per cent (70) receiving a new histopathological diagnosis, or a definitive one from a range or radiological possibilities, both diffuse (10 of 14) and diffuse lesions (60 of 85, both 71%). Forty-five per cent (44 of 99) had sufficient clinical data to ascertain treatment before and after biopsy. A significant change in treatment occurred in only 16 per cent (seven of 44) without a significant difference between diffuse (33% [three of nine]) and localized (11% [four of 35]) lesions (P = 0.38). Twenty-five per cent (25 of 99) of patients undergoing lung biopsy died. Lung biopsy is performed for conditions with a high mortality rate. The procedure yields a definitive diagnosis in the majority of cases but infrequently changes therapy.