Biomedical research in oncological diseases, particularly focused on the study and understanding of the molecular mechanisms involved in cellular transformation, is opening new possibilities for the development of new and more efficient strategies for diagnosis and treatment. The generation and practical application of the results derived from molecular genetic studies in cancer, has evolved in parallel with the development of technological tools that allow us to get a global vision of diverse cellular processes, both in the normal and pathological states. This combination of basic research and technological application, has created methodologies that allow us to analyze the three principal levels of Molecular Genetics, the Genome (DNA, archive of the genetic information), the Transcriptome (RNA, expression of the genetic information), and finally, the Proteome (proteins, functional aspect of the genetic information). The vast amount of information obtained due to these advancements has begun to modify our fundamental vision about oncological diseases, and together with the traditional analytic tools, they hold the promise of changing the ways we classify, detect, diagnose and treat cancer. In this review, we present some of this methods for global genetic analysis, involving the three levels of genetic organization: the genome, with the Human Genome Project, comparative genomic hybridization and chromosome painting; the Transcriptome, with Serial analysis of Gene Expression and DNA microarrays; and the proteome, with bidimensional protein electrophoresis and antibody-microarrays. In each case, together with a brief description of the method, we also present the impact of every one of them on the study and management of neoplastic diseases.