Neutrophils play an important role in human innate immunity, but their role in cancer biology was underestimated. It was seen that a high neutrophil-to-lymphocyte ratio is correlated with poor outcomes in patients with cancer. Recently, the role of neutrophils in tumor progression has been increasingly noticed. Tumor-associated neutrophils (TANs) have a critical impact on the tumor microenvironment by producing cytokines and chemokines. Interestingly, TANs (similar to macrophages) have both antitumor (N1 phenotype) and protumor (N2 phenotype) activities. N2 neutrophils can promote cancer by inducing mutation, tumor growth, angiogenesis, and metastasis. Unfortunately, most of the studies on TANs have been performed on animal models, and limited data are available regarding the role of TANs in humans. Understanding the role of TANs in human cancers is essential since they play a crucial role in tumor growth, angiogenesis, and metastasis. Targeting TANs could have promising results in cancer management. This chapter discusses the different aspects of TANs in cancer biology and highlights TANs as a therapeutic target in cancer therapy.