Iranian crack cocaine is one of the drugs of abuse used in Iran which can negatively impact the immune system and its regulation. This study aims to determine the effect of one month of administration of crack cocaine on Wistar rats. Methods and materials: Wistar rats were divided into 4 groups of 10 and received crack injection intraperitoneal for one, two, and three weeks respectively, and the last group was control .Blood samples were collected 24 hours after the last injection and neutrophil and lymphocyte counts were studied using optical microscope. Results: Neutrophils count decreased significantly after a one-month crack administration, while Lymphocyte count had a significant increase. Conclusion: Our findings showed that Iranian crack cocaine can reduce immune system functions in rat models.