For evaluating and monitoring of both inpatients and outpatients, complete blood count is one of the commonly performed investigations but at times it is challenging to evaluate all the blood samples on the collected day due to various factors like manpower shortages, weekends, and a single cell counter. Inspite of all these conditions we need to provide accurate report to patients. Hematology results are often influenced by the time between blood sampling and measurement as well as the storage conditions during sample delivery. This is because the hematological elements have limited stability in EDTA-anticoagulated blood. The stability of hematological parameters has improved after the anticoagulated blood is refrigerated.The aim is to investigate the effect of room temperature and refrigerated storage on complete blood counts and peripheral blood smear on automated hematological parameters. Blood samples were collected from 100 patients. Hematological parameters like Hemoglobin, PCV, MCV, MCH, MCHC, Platelet count, Red blood cell and White blood cell count were analyzed in room temperature storage and refrigerated storage at 40c for 24hrs using automated hematology analyzer. Peripheral blood smear from samples stored at room temperature and at 40 C in refrigerators for 24hrs were also examined.The study revealed RBC count and Hemoglobin were unaffected by storage at room temperature and refrigerated storage. Whereas MCV showed significant increase with storage at room temperature and WBC showed decrease in count with storage at room temperature that is preserved by refrigeration.