Hematology histograms constitute the graphical representation of data related to the number, morphology, and composition of blood cells, and are readily available during the full blood count analysis from the modern hematology analyzers. Blood histogram curves accompanying the numerical findings of full blood count often provide evidence of underlying pathology in a direct and visualized manner and guide the differential diagnosis and further investigation in patients with acute and chronic diseases. This study presents the basic principles of hematology analyzers and the interpretation of histograms and focuses on their connection with pathological conditions encountered in clinical practice and routine of hematology laboratory. For this purpose, a series of common clinical cases with typical qualitative and quantitative changes in blood figures are presented. The full blood count analysis was performed in our laboratory with the Beckman Coulter Unicel DXH 800 hematology analyzer. The morphology, the base width, and the displacement of the histogram curves were used to check the validity of instrument flags, to rule out pre-analytical or analytical errors and for the initial diagnostic approach of hematology diseases, infections and disorders with secondary hematological manifestations. The above data combined with the clinical history and the microscopic examination of the peripheral blood smear contributed to the correct and timely diagnosis and treatment decisions.