Abstract: The present invention provides a novel crystalline form of linezolid referred to herein as Form IV as well as methods for the preparation and use of Form IV. The present invention provides pharmaceutical compositions that comprise therapeutically effective amounts of Form IV that can be used to treat patients suffering from gram-positive bacterial infections. Various processes for making crystalline linezolid Form IV are disclosed.

Abstract: The present invention provides a novel crystalline form of linezolid referred to herein as Form IV as well as methods for the preparation and use of Form IV. The present invention provides pharmaceutical compositions that comprise therapeutically effective amounts of Form IV that can be used to treat patients suffering from gram-positive bacterial infections. Various processes for making crystalline linezolid Form IV are disclosed.

Abstract: Novel crystalline forms of Linezolid, designated as Form TIII, Form V, Form VI, Form IX, Form X, Form XII, Form XIV, Form XVII, and Form XVIII, are disclosed. The novel crystalline forms are characterized by powder X-ray diffraction, FTIR and FTRaman spectroscopy, and differential scanning calorimetry. Methods of preparing the novel crystalline forms, pharmaceutical compositions comprising the novel crystalline forms, and methods of using the novel crystalline forms to treat gram positive bacterial infections are also described. Amorphous Linezolid is also disclosed.