The most commonly performed blood test is complete blood cell count. This test includes hemoglobin, white blood cell count, platelet count, and detailed red blood cell indices. Automated complete blood count also give information for "differential" which gives information about percentages and absolute numbers of different subgroups of white blood cells. This test is necessary in diagnosing anemia, hematological cancers, infections, acute hemorrhagic states, allergies, and immunod-eficiencies. Also it is used for monitoring side effects of certain drugs. A pediatrician is frequently challenged for evaluating complete blood count as a part patient's assessment. An enhanced and complete understanding of this laboratory test is essential for providing quality care of sick and normal children. Here in this paper, we want to share key laboratory interpretation strategies for complete blood count and some clues for differentiating normal from deviations and true problems.