This study was designed to investigate the effectiveness of meloxicam in the treatment of proventricular dilatation disease induced by challenge with avian bornavirus (ABV), strain M24. Three groups of 4 cockatiels were employed. Group 1 was challenged with ABV alone, group 2 was challenged with ABV and 20 days later began daily oral meloxicam treatment, and group 3 received daily oral meloxicam alone. All birds in groups 1 and 3 remained in apparent good health and maintained their weight until being euthanized on day 150 after challenge (group 1) or day 130 of treatment (group 3). In contrast, group 2 birds died or were euthanized on or before day 98 because of severe weight loss and depression. Necropsy and histopathology results indicated that all birds in group 2 had pathologic evidence of proventricular dilatation disease. ABV was detected by reverse transcriptase polymerase chain reaction testing in all the major organs of the group 2 birds. The proventriculus was enlarged in 2 birds in group 1, and 75% of the birds in this group had ABV detectable in all their major organs. No significant lesions were observed in group 3 birds.