The Kyushu Hematology Organization for Treatment (K-HOT) Study Group was organized in 1999 to study hematological disorders diagnosed in the participating institutions in the Kyushu district. We registered all new patients with hematological disorders and from February 2000 to the end of 2003, a total of 2908 patients had been registered. They include non-Hodgkin's lymphoma in 803 patients, leukemia in 556, multiple myeloma (MM) in 276, myelodysplastic syndrome in 273, and adult T-cell leukemia/lymphoma (ATL) in 269 followed in a decreasing order by idiopathic thrombocytopenic purpura, aplastic anemia, and other benign hematological disorders and myeloproliferative disorders. The annual incidence of MM is estimated to be much higher than that previously reported. It is also confirmed that ATL is still one of the frequently encountered lymphoid malignancies in the Kyushu district.