The paper presents a retrospective analysis of long-term follow-ups (from 1959 to 2000) of 86 patients with acute pro-myelocytic leukemia, a rare type of hemoblastoses. The specific features of this form of leukemia is that blast cells of the bone marrow and peripheral blood have a specific granularity that plays a decisive role in the development of the severe hemorrhagic syndrome leading to patients' death. The morphological, cytochemical, cytogenetic, electron microscopic, and biochemical features of blast cells in this disease and its pathogenesis, clinical presentation, and treatment are considered. An extract from the records of a female patient who has had a complete clinical and hematological remission for 22 years is given. The follow-up of such a prolonged remission has not been covered in the Russian literature.