A large variety of infectious diseases may involve the rhinosinusal tract. They include bacterial, viral, fungal, and parasite infections. These infections can induce an acute and/or a chronic inflammatory reaction. They can develop both in immunocompetent or in immunodeficient patients. Clinically, the consequences of these infections are variable, but a few of them have to be rapidly diagnosed for an immediate specific treatment. This article describes the pathologic features of a variety of infectious diseases that surgical pathologists may encounter in analysis of biopsy specimens taken from the rhinosinusal tract.