Resistance to glucocorticoid (GC) is a significant clinical problem in some cases of acute lymphoblastic leukemia (ALL). Current methods of assessing GC resistance are time consuming and have limited reproducibility; in this study, we sought to define a new method of evaluating GC sensitivity and resistance in vitro. Based on the mechanisms of GC resistance, we hypothesized that the dual-luciferase report (DLR) assay could reflect the transcription effects of GC downstream of the GC-glucocorticoid receptor signaling pathway, thereby allowing the evaluation of reactions to GC. Sixty-two patients with differential GC response were included in this study. The prednisone induction test was used to divide the children with ALL into two groups: GC sensitive (GCS) and GC resistant (GCR). DLR assay was later conducted on those patients to evaluate its value for diagnosis of the GC reactivity. Receiver operating characteristic curves were used to identify the optimal assay cutoff for identifying response to GC. Using the DLR assay analysis, we found that GCR subjects showed significantly lower reporter/control ratios for luciferase, as compared with GCS subjects. The optimal cutoff value for GC response was 0.67, with sensitivity of 77.1% and specificity of 93.3%. The DLR assay results were consistent with prednisone induction test results. Further, the DLR assay was simpler, more sensitive, and less time-consuming than the prednisone induction test. Our study showed that the DLR assay is relatively fast, simple, and sensitive. Accordingly, it could be useful for detecting GC response in children with ALL.