A very old patient (82 years old) with chronic proliferative disease was treated by hydroxyurea, and its dose was adjusted according to the counts of platelets and leukocytes. Subsequently, the disease transformed into acute myeloid leukemia (AML). When the dose of hydroxyurea is increased, agranulocytosis and infection appeared. Since the patient was very old and had a few multiple comorbid diseases, it was very difficult for his treatment. After a consultation attended by physicians from disciplines of hematology and respiratory diseases, The comprehensive adjustment was made to strengthen supporting treatment. In present, the condition of the patients is fair, and relatively stable, but the overall prognosis is poor. How to improve the treatment of hematological diseases in very old patients is the issue urgent to be solved by non-hematological geriatric physicians.