Acute promyelocytic leukemia (APL) with the PML-RARA fusion gene can be effectively cured using molecular-targeted therapies, which require both detection and quantification of the PML-RARA fusion gene. Here, we developed a rapid assay for identifying and measuring the PML-RARA fusion gene in patients with APL using droplet-reverse transcription-polymerase chain reaction (droplet-RT-PCR) and instant quality-fluorescence in situ hybridization (IQ-FISH).