Abstract : Environmental pollution has been identified as one of the growing up worldwide problems. One of the most affecting kinds of pollution is the noise. The negative impact of noise has been studied on many body systems. Here, the effect of noise pollution on some hematological and biological parameters such as; white blood cells (WBCs), neutrophils, lymphocytes, monocytes, eosinophils, and spleen weight were studied. Twenty-one Sprague Dawley adult male rats (165-185g b.wt) were randomly divided into three groups, 7 rats in each group. The first group was not exposed to noise and considered as control group, second group was exposed to low level of noise (LLN), 50-55 dBA, while the third group was exposed to high level of noise (HLN), 90-95 dBA. The exposure time was 3 hrs per day for two weeks. At the end of the experiment, rats were sacrificed, blood samples and spleens were collected. The results showed that the total count of WBCs, lymphocytes, and monocytes has been increased significantly (P<0.01), (P<0.0001) and direct proportionally with noise level. There was no effect (P>0.05) of LLN on neutrophils, while the HLN showed significant increase (P<0.05) count in comparison with control group. Surprisingly, there was no significant (P>0.05) change in eosinophils counts. Relative spleen weight increased significantly (P<0.01) and (P<0.0001) among the groups with levels of noise pollution. The change in hematological and spleen parameters are considered as negative impact signs on the immune system that most likely caused by noise exposure. Our work clearly showed the impact of noise pollution on the immune system of mammals, it is a very important finding in term of warning the public about the impact of noise pollution and that could be useful for future considerations.