Background Glucocorticoids play an important role in the treatment ofacute lymphoblastic leukemia (ALL), but can cause side effects such as suppression of the hypothalamic-pituitaryadrenal (HPA) axis. Suppression of the HPA axis causes adrenal insufficiency, disturbs the cortisol response to stress, and may be a cause of morbidity and mortality in children with ALL. Objective To evaluate adrenal function in children with ALL after induction chemotherapy with high dose glucocorticoids. Methods The adrenal function of 20 children with ALL was evaluated using a standard dose (250 μ g) adrenocorticotropin hormone (ACTH) test performed before and after a 6 week of treatment with glucocorticoids induction phase chemotherapy, which was followed by a week period tapering off. Adrenal insuffien cy was defined as blood cortisol level of < 18 μg/dL. Results Adrenal insufficiency was found in 14/20 subjects after the induction phase followed by a week period of tapering off. Median cortisol levels pre- and post-stimulation before induction phase were 14.72 (range 2.0 1- 46. 1) μg/dL and 29.29 (range 21.65 - 55 .15) μg/dL, respectively. Median cortisol levels pre- and poststimulation after induction phase were 5.87 (range 0.2 - 20.53) μg/dL and 10.49 (range 0.33 - 28.69) μg/dL, respectively. Clinical signs and symptoms did not differ between those with and without adrenal insufficiency. Conclusion Of 20 children with ALL, 14 develop adrenal insufficiency after a 6-week induction therapy with glucocorticoids and followed by a week period of tapering off. No specific clinical signs and symptoms are identified to be related to the adrenal insufficiency.