Breast cancer is one of the most common cancers diagnosed in both countries with high and low levels of socio-academic development. Routine, regular screening tests being introduced in an increasing number of countries make it possible to detect breast cancer at an early stage of development, as a result of which the trend in the incidence of metastatic breast cancer has been decreasing in recent years. The latest guidelines for the treatment of this tumor do not recommend axillary dissection, which limits the need for rapid assessment of the nodes during surgery. Regardless of the progression of the disease, lymph node biopsy and their analysis is one of the most common diagnostic methods for detecting metastases. Systems using one-step amplification of nucleic acids have been present in the diagnosis of breast cancer for nearly 20 years. The one-step nucleic acid amplification (OSNA) test semi-quantitatively detects the number of cytokeratin 19 mRNA copies, a well-known tumor marker, which can be used to infer the presence of metastases in non-sentinel lymph nodes (SLN). Aim: OSNA is a widely used molecular method for SLN, intra-, or postoperative analysis. Its high accuracy has been proved over the years in clinical use. In this review, we checked current state of this technology and compared it to its competitors in the field of breast cancer diagnosis in the era of Axillary Lymph Nodes Dissection (ALND) importance decrease with intention to foresee its further potential use. Objectives: To evaluate OSNA current place in breast cancer diagnosis and treatment we compared OSNA to other lymph node assessing methods. We based our review on original articles and metanalyses published in the last decade. The research was conducted with PubMed, Science Direct, Google Scholar, and NCBI databases. The collected data allowed us to assess the accuracy of OSNA, its cost effectiveness, and its application in other cancers. Results: Regardless of the progression of the disease, a lymph node biopsy and its analysis constitutes one of the most common diagnostic methods for detecting metastases. The OSNA method is characterized by high sensitivity and specificity, and its predictive value has been confirmed by many studies over the years. While its cost effectiveness is still a matter of discussion, this method has been tested more thoroughly than other new lymph nodes assessing technologies. Conclusions: Despite the emergence of competing methods, this test is still widely used as a routine intraoperative examination of lymph nodes. Research carried out in recent years has proved its effectiveness in the diagnosis of other cancers, in the research field, and as a provider of additional data for prognosis improvement.