The immune system and inflammation are involved in the pathological progression of various psychiatric disorders such as depression or major depressive disorder (MDD), generalized anxiety disorder (GAD) or anxiety, schizophrenia, Alzheimer's disease (AD), and Huntington's disease. It is observed that levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and other markers are highly increased in the abovementioned disorders. The inflammation and immune component also lead to enhance the oxidative stress. The oxidative stress and increased production of reactive oxygen species (ROS) are considered as important factors that are involved in pathological progression of psychiatric disorders. Increase production of ROS is associated with excessive inflammation followed by cell necrosis and death. The psychotropic drugs are mainly work through modulations of neurotransmitter system. However, it is evident that inflammation and immune modulation are also having important role in the progression of psychiatric disorders. Rationale of the use of current psychotropic drugs is modulation of immune system by them. However, the effects of psychotropic drugs on the immune system and how these might contribute to their efficacy remain largely unclear. The drugs may act through modification of inflammation and related markers. The main purpose of this book chapter is to address the role of current psychotropic drugs on inflammation and immune system. Moreover, it will also address the role of inflammation in the progression of psychiatric disorders.