This book aims to approach the epidemiology, diagnosis and management of infectious complications related to the use of biologic and targeted therapies. The first part is a general overview on the epidemiology and prevention of infections with the use of these agents. Timelines, pre-treatment evaluation, use of vaccines and travel counseling. In the second part, we will analyze the specific risk of infections associated with the use of the most important agents. The third part approach the problem on a syndromic point of view. For example, how to evaluate pulmonary infiltrates in a patient receiving biologic agents. This part III includes the most difficult and conflicting syndromes that clinicians may face when evaluating these patients.