This issue of Pathology Patterns presents a series of review articles in molecular pathology and molecular diagnostics that cover a wide variety of applications of new technologies recently integrated into many clinical laboratories and pathology departments. In order for the benefits of molecular pathology to outweigh its inherent costs, these new procedures must be integrated into the assessment of total disease management to fully observe how the benefits outweigh the costs and effects on patient outcome. Major financial benefits can be achieved with molecular testing because of ability to reduce the use of less sensitive and specific tests, and unnecessary diagnostic procedures and ineffective therapies.