Objective To verify the presence and location of the NLS-RARα protein in the peripheral blood tumor cells of patients with acute promyeolic leukemia (APL). Methods Western blotting analysis was used to identify the NE enzyme in the peripheral blood tumor cells of APL patients. The nucleoprotein in tumor cells was prepared and NLS-RARα protein was detected by Western blotting analysis. The expression and location of NLS-RARα protein in peripheral blood tumor cells of APL patients were examined by FITC/DAPI double immunofluorescence staining and FITC/PI double staining laser confocal microscopy. The expression and location of NLS-RARα protein in NB4 cells infected with recombinant adenovirus Ad-NE was used as positive control and those of wildtype RARα in the neutrophils of healthy controls were taken as negative control. Results Positive control was successfully established. NE enzyme and NLS-RARα protein were expressed in peripheral blood tumor cells of APL patients. Immunofluorescence and laser confocal findings indicated that NLS-RARα protein was mainly located at the nuclei of peripheral blood tumors cells in APL patients. Conclusion NLS-RARα protein has been successfully detected by 3 different methods in the peripheral blood tumor cells of APL patients and its intracellular location has also been proposed, which can contribute to the early diagnosis and recurrence monitoring of APL.