Transfusion-related acute lung injury (TRALI) is the leading cause of mortality from transfusion therapy. Recipient, donor, and blood product risk factors may have important roles in the occurrence of TRALI. A case-control pilot study of 6 TRALI cases in which HLA-antibody concordance was found and 20 control subjects was conducted to evaluate recipient and donor predictors of TRALI. By using stratified exact logistic regression, characteristics of the recipients, donors, and blood products were analyzed and the results reported as odds ratios. The risk for TRALI was increased per unit of whole blood transfused (odds ratio, 3.0 per unit; P = .0098). A larger prospective case-control study is underway to determine recipient, donor, and blood product risk factors associated with TRALI.