The aim of the present study was to obtain basic knowledge of the basic hematological parameters of shark catfish (Helicophagus waandersii Bleeker, 1858 ), that one of the commercial native species in the Mun river and the Mekong river basin. 30 fish were captured twice in August and December, 2007 from the Mun river in Khong Jiem District and the Mun–Chi watershed in Wharinchumrhab District, Ubon Rajchathani Province, respectively.Those hematological parameters included a number of leukocytes, hemoglobin, hematocrit, differential leukocyte count, size measurement of erythrocytes and leukocytes, the percentage of thrombocytes in leukocytes and the percentage of raticulocytes. Number of leukocyte count, hemoglobin and hematocrit measurement were determined by the hemocytometer method, cyanomethemoglobin method and microhematocrit method, respectively. All replicates were used for calculation of mean values. The result of this study is in processed.