Studies on the biology of cancer are multiplying and have been giving significant repercussions on the care of cancer patients, and there is a growing need to evaluate the biology of the tumor. Conventional tissue biopsies currently represent the gold standard in the diagnosis of cancer, but they are not suitable for serial analysis because of the need for invasive procedures, besides being able to present a high risk of life and also impossibility of reaching surgical in some tumors. To solve this obstacle, the use of the Liquid Biopsy, which analyzes the presence of biomarkers released by cancer cells, such as circulating tumor cells (CTCs), tumor cell DNA (ctDNA) and exosomes is being discussed. These techniques are non-invasive or minimally invasive and collect their samples from peripheral blood, plasma and serum, urine, saliva and cerebrospinal fluid (CSF). As they are already being used in the treatment of several histopathological types of cancer, these new techniques generally represent a revolution in the understanding of early diagnosis, choice of personalized treatment, follow-up of the treatment response in real time, detection of minimal residual disease and prognosis for malignant neoplasms. The objective of this study was to present a literature review to clarify the fundamental molecular and clinical aspects involved in this revolutionary diagnostic technique by extracting the data from the sample. Keywords: Liquid Biopsy. Oncology.: literature review