In this study, we investigated the effect of the static magnetic field (SMF) on white blood cells (WBCs) for female albino rats using a fabricated exposure system of SMFs. Five main groups of animals exposed to 2.4±0.2 milli-Tesla (mT) for four weeks continuously. Five main groups (each group= 4 subgroups) have exposed to a different time of exposure; 1hr, 2hrs, 4hrs, 6hrs and 8hrs/day, respectively. Collected blood samples examined and compared with control values. The results proved that the time of exposure influences the WBCs significantly. One hour of exposure has increased the WBCs counts tremendously (from 50%-79%) in all weeks. However, the 8hrs of exposure reduced WBCs counts highly (from 71%-51%). The 3 weeks exposure trend was an increase, except the 8hrs/day exposure.