INTRODUCTION
The pathology laboratories have a markedly enriched with advances in immunology and molecular biology, which have put a veritable arsenal of new techniques for diagnosis that, until recently, were exclusively morphological.

Using molecular biology techniques is a fact in many of our laboratories and has the same meaning as was the application of electron microscopy or immunohistochemistry in a past still close. As was the case with these early techniques are confusing and the proportion of professional skeptics and contrary to its implementation as routine techniques decreases over time and with the growing success of them.

It is necessary for discipline importance of pathology not languish, to be imbued with new knowledge and apply them properly, which at the earliest begin to scrutinize the awesome secrets that lie DNA.

Genetics:
*Prenatal diagnosis
*HLA typing
*Genetic rearrangements
*Detection of sperm aneuploidy
*Genetic mapping

Microbiological Diagnosis:
*Rapid diagnosis of viral infections
*Detection of microorganisms in infected cells / processed
*Determining the genetic relationship between various types of microorganisms like
*To correlate the presence / expression of viral agents / infectious neoplastic tissues.
*To determine the antibiotic resistance of bacteria.
*Epidemiology of infections
*Detect and quantify microorganisms difficult to culture or for which there are no serological reagents.
*Detecting specific transforming regions in viruses

Diagnosis and classification of tumors and establishment of a prognosis:
*Detect gene rearrangements
*Detecting rearrangements in human tumors with karyotypic abnormalities consistent
*Detect molecular rearrangements / gene expression abnormalities in the absence of abnormal karyotype
*Study of structure / expression of oncogenes
*Detection of gene amplification / drug resistance
*Diagnosis of cell lineage based on gene expression