There has been growing work in the field of Named Entity Recognition (NER) and a lot of research has been done in this direction in last two decades. Particularly, a lot of progress has been made in the biomedical domain with emphasis on identifying domain-specific entities and often the task being known as Biological Named Entity Recognition (BIO-NER).Biomedical named Entity Recognition is a crucial step towards efficient texts analysis in the medicine. The biomedical domain, due to its complicated language, has consistently lagged behind. Our aim is to extract named entities such as Gene, Protein or Cell Types. This paper looks at the challenges perceived by the researchers in BIO-NER task and investigates the works done in the field of BIO-NER by using the multiple approaches available for the task.