The objective of this report is to analyze the value of CMV viral load (VL) in bronchoalveolar lavage (BAL) in recipients of allogeneic hematopoietic stem cell transplantation (AHSCT) and to analyze the concordance between CMV quantification in plasma and BAL samples. Fifty-six patients were included; in 16 (28.6%) patients with symptoms of lung disease a BAL sample was collected, 7 (43.7%) patients had a VL > 150 copies/mL (six had probable CMV pneumonia). Patients with CMV pneumonia were female (100%), of median age 53.5 years, and the median time from transplantion to onset of symptoms was 67.5 days. Pneumonia was early in three cases (incidence 5.4%). Median BAL VL was 53 250 copies/mL and plasma VL was 538 copies/mL (in one patient, the plasma VL was negative). Three (50.0%) patients had an improvement in the first week of treatment, and plasma VL became negative; the other 3 (50.0%) patients died with a CMV pneumonia refractory to treatment. Therefore, any value of CMV VL in BAL, especially if it is greater than plasma, with compatible signs or symptoms, should be considered suggestive of CMV pneumonia in recipients of AHSCT and they should receive specific treatment.