Alcaligenes xylosoxidans which is an aerobic, non-fermentative gram-negative bacillus found in aqueous environments and human flora, can lead to opportunistic infections. It causes infections in elderly, immunocompromised patients, patients with chronic disorders or premature infants. In this report, a case of A.xylosoxidans bacteremia that developed in a child with acute lymphoblastic leukemia (ALL) was presented. Four years old male patient under ALL induction therapy was admitted with symptoms of lethargy, headache, somnolence, and fever (39 degrees C). Cerebrospinal fluid, blood, throat and urine cultures were taken from the patient and empirical treatment with sulbactam cefoperazon and amikacin was initiated. Blood cultures in BacT Alert 3D (Bio Merieux, France) revealed the growth of a gram-negative coccobacillus. The agent which was non-fermentative, indol and H(2)S negative, was identified as A.xylosoxidans by AN 20 NE (Bio Merieux, France). Since fever continued under the current antibiotic treatment, the therapy was switched to imipenem (90 mg/kg 3x/day) and the patient's condition improved markedly after 24 hours. Disc diffusion susceptibility testing of the isolate revealed that it was resistant to ampicillin, cephalothin, cefuroxime, cefoxitin, cefotaxime, amikacin, netilmicin and gentamicin; susceptible to amoxicillin clavulanate, piperacillin tazobactam, seftazidime, cefepime, imipenem and ciprofloxacin. Following 14 days of imipenem therapy, the patient recovered and discharged from the hospital on routine follow-up. It is important to consider A.xylosoxidans as a possible causative agent particularly in the infections that develop in high risk patients at oncology, dialysis and neonatal intensive care units.