Thalidomide is a drug that, since its development, has made history in the world 
of medicine--having been withdrawn and now has returned with a boom as an 
anticancer and immunomodulatory drug. However, its mode of action in various 
diseases (i.e. different types of hematologic malignancies, solid tumors) as 
well as in various infections (i.e. pneumonia, tuberculosis, HIV infection etc.) 
and related inflammatory conditions is not well understood. As the immune system 
plays an important role in the pathogenesis of both infection-related as well as 
noninfectious (i.e. cancer) inflammatory diseases, much research has been done 
in the past few years to discover and design better immunomodulatory agents. 
Such immunomodulatory agents should be able to target the immune system in such 
a way that host suffers minimum damage and normal function of the immune system 
remains intact. In the present review an attempt is made to highlight the 
immunomodulatory action of thalidomide in various pathologic conditions.