Results of quantitative shell vial cultures of cell and supernatant fractions of bronchoalveolar lavage (BAL) fluid from lung transplant recipients were compared with results of transbronchial lung biopsies. Cytomegalovirus (CMV) was present in both the cell and supernatant fractions, including 28 (80%) and 29 (83%), respectively, of 35 BAL samples with corresponding biopsies that showed evidence ofCMV pneumonitis and 34 (15%)and 75 (33%), respectively, of227 BAL samples with corresponding biopsies that did not. Cultures of unseparated BAL fluid had a similar yield to cultures of supernatant. Virus titers of cell fractions and supernatants from BAL samples with corresponding biopsies that were positive for CMV pneumonitis were higher than those from BALs with negative corresponding biopsies. Culture of the unseparated fluid is recommended for simplicity and to maximize detection of CMV. Quantitative results may help in the identification of CMV pneumonitis, but additional studies are needed before quantitative cultures can berecommended for routine use.