The association of cytomegalovirus (CMV) infection with the development of bronchiolitis obliterans syndrome (BOS) is unclear. We studied 341 lung transplant recipients to assess whether histopathologically diagnosed CMV pneumonia treated with ganciclovir was a risk factor for development of BOS and patient survival. We also analyzed the relationship between CMV donor/recipient serologic status and BOS plus the temporal association between acute rejection and CMV pneumonia. Freedom from BOS for patients with (n = 151) and without (n = 190) CMV pneumonia was 83 and 90% (1 year), 52 and 56% (3 years), and 29 and 38% (5 years), respectively (p = 0.2660). Cumulative survival of patients with and without CMV pneumonia was 90 and 93% (1 year), 70 and 74% (3 years), and 58 and 63% (5 years), respectively (p = 0.1811). There were no significant differences in either development of BOS or patient survival with any combination of donor/recipient serostatus for CMV. Acute rejection occurred in the month preceding CMV pneumonia in 62 of 193 (32%) cases. Histopathologically confirmed CMV pneumonia treated with ganciclovir is not a risk factor for BOS or patient survival, nor is any particular CMV serologic donor/recipient group. CMV pneumonia often follows acute rejection, perhaps as a result of augmented immunosuppression.