Hematological diseases in childhood occur frequently. Analyses of hematological status as well as standard biochemical analysis of blood, as a result of hematopoetic system function, are of great importance in detection and recognition of these diseases. All hematological diseases appear as disturbance of hematopoetic system function at the level of the production and viability in blood flow; this disturbance is reflected on the hemogram and biochemical analyses of blood plasma and serum. The basic hematological parameters of blood diseases (except disturbance of blood coagulation) are Total blood count cells (erythrocytes, leukocytes with differential leukocytes formulae, trombocytes) hemoglobin concentration, amount of hematocrit (PCV, packed cell volume), erythrocytes sedimentation rate erythrocytes osmotic fragility. Among the standard biochemical analysis the determination of total bilirubin in the calculation fraction of indirect bilirubin, the amount of serum iron and transferrine (TIBC), serum copper and ceruloplasmin are in use in these diseases. Hemoglobin electrophoresis is also use. The measurement of lactate dehydrogenase activity and other enzymological analyses are rarely performed. The basic idea of this report is the evaluation of another biochemical possibility with the aim to understand the nature of hematological disorders by the use a large spectrum of enzyme analyses, which are present in different blood cells and with direct reflection on the serum enzyme activities.