A 4.5-yr-old, captive-bred, male bearded dragon (Pogona vitticeps) presented for lethargy, anorexia, and increased mucoid salivation with upper respiratory clicks. Diagnostics were declined and the bearded dragon was prescribed ceftazidime 20 mg/kg i.m. q 72 hr. The patient presented again 1 wk later with a marked monocytosis, heterophilia, and lymphocytosis, and a clinical diagnosis of chronic monocytic leukemia was made. Chemotherapy with cytosine arabinoside (100 mg/m² over 48 hr i.v.) was initiated. Forty-four hours into the treatment the dragon became acutely unresponsive and died within 1 hr. Adverse effects as a result of i.v. cytosine arabinoside therapy were not identified despite previous reports suggestive that the drug induces renal failure.