MicroRNA-204 (miR-204) level was negatively correlated with arsenic trioxide (ATO)-induced decrease in cell viability and baculoviral inhibition of apoptosis protein repeat-containing 6 (BIRC6) expression in acute myeloid leukemia (AML) cells. (A) AML-5 or HL-60 cells were treated with different concentrations of ATO (0, 1, 2.5, 5, or 10 μmol/L) for 48 h. The miR-204 level was determined by quantitative real-time PCR. (B) Cell viability was assessed by cell counting kit (CCK-8) assay. (C) The mRNA expression of BIRC6 was examined by quantitative real-time PCR. *p < 0.05; **p < 0.01 versus 0 μmol/L, n = 6–8. (D, E) The cell viability (D) and BIRC6 expression (E) were negatively correlated with miR-204 level, respectively. (F) Forty-eight cases of AML patients with a good response to ATO were selected after 2-year outpatient maintenance, and then the RNA of AML samples was harvested. Quantitative real-time PCR analysis of miR-204 and BIRC6 mRNA levels in primary AML samples before and after ATO treatment. **p < 0.01 versus AML (before ATO treatment).