Analyses of the dynamics of frequency of hematological diseases were conducted in the area of former Semipalatinsk nuclear test site and in different zones of radiation risk during the period of 1994-2003. Hematological diseases were diagnosed in 1,667 persons who were directly exposed to radiation, including their second and third generations. General morbidity of hematological diseases in this period gradually increased from 19.8 to 23.8 per 100,000 population. To observe dynamics of structure of hematological morbidity for the 10-year period we compared the proportion of each disease in 1994, 1999, 2003, i.e., at the beginning, the middle and the end of the observation period. In the analyses, the specific weight of chronic lymphoid leukemia for this period was reduced, the specific weight of acute leukemia increased in 1999 and then decreased in 2003, while chronic myeloid leukemia had no positive dynamics. The increasing tendency of specific weight of autoimmune diseases and pernicious anaemias was marked. There was still a high frequency of blood diseases in the zones of extreme and maximal radiation risk. The changes in structure of hematological diseases in a zone of the former Semipalatinsk nuclear test site are probably related to a hereditable predisposition of radiation induced immune imbalances.