ATRA is extremely effective for inducing clinical remission in APML. The presence of PML/RAR-alpha fusion gene produced as a result of the unique chromosomal translocation in APML is a marker of the sensitivity to ATRA therapy. Further research is needed to elucidate the mechanisms by which the development of the fusion protein in APML leads to the arrest of myeloid differentiation. ATRA leads to rapid resolution of the coagulopathy associated with APML. There is a major clinical benefit since coagulopathy often causes early fatal hemorrhage. The effectiveness of ATRA in APML can serve as a paradigm for the use of differentiation therapy in human malignancies.