Majority of the blood banks in Nigeria still practice whole blood banking. The changes associated with the storage of blood in our blood banks have not been reported. This study was aimed at bridging this gap. Blood (450 ml) was drawn from ten healthy volunteer donors into CPDA-1 anticoagulant and placed on the quarantine shelf of the blood bank refrigerator maintained at 2-8°C. Blood bags were screened for HCV, HBsAg, Syphilis and HIV 1&2 and were confirmed negative. Samples were collected at 1, 7, 14, 21 and 28 days and tested for hematological and biochemical using the PE-600 fully auto Haematology analyzer (China) for hematological parameters, Excite -40 ESR analyzer and Prestige 24i automated clinical analyzer for biochemical parameters. Comparison of day 1 versus day 7 revealed that the granulocytes were drastically reduced from 1.93 × 109 /L on day 1 to 0.33 × 109/L on day 7 (F=48.79, p=0.000, ESR values increased from 2.90 mm/hr on day 1 to 6.60 mm/hr on day 7 (F=7.45, p=0.013. For biochemical parameters, there was a significant decrease in Na value from 137.38 mEq/L on day 1 to 135 mEq/L on day 7 (F=43.66, p=0.000). Analysis of variance (ANOVA) showed that at the end of 28 days, there was significant changes in WBC, differential and absolute leucocytes, MPV, PDW, and ESR, albumin and potassium were significantly affected among the biochemical parameters. No significant changes were observed in Hb, PCV and other hematological parameters throughout the study. Rapid degeneration of leukocytes could lead to immunodulation related to blood transfusion. Whole blood should be leukodepleted before storage if it must be used beyond one week.