Heterocyclic compounds have a role in most fields of sciences such as medicinal chemistry, biochemistry also another area of sciences. More than 90% of new drugs contain heterocycles and the interface between chemistry and biology, at which so much new scientific insight, discovery and application is taking place is crossed by heterocyclic compounds. Compounds derived from heterocyclic rings in pharmacy, medicine, agriculture, plastic, polymer and other fields. Most active heterocycles that have shown considerable biological actions as anti-fungal, anti-inflammatory, anti-bacterial, anti-convulsant, anti-protozoal, anti-allergic, herbicidal, anti-cancer activity. Heterocyclic compounds are a highly valuable and unique class of compounds. Different heterocyclic analogues have been evaluated for their diverse biological activities. Heterocyclic compounds are present in abundance in our surroundings. They owe their importance in the biological system due to uniqueness in their structural skeleton parts. They are naturally found in nucleic acid, vitamins, anti-biotics, hormones etc. Nitrogen containing heterocyclic compounds are an important class of heterocyclic compounds that has paid significant contribution towards medicinal chemistry. This review highlights the trends in the use of nitrogen-based moieties in drug design and the development of different potent and competent candidates against various diseases. This review shall give researchers access and detailed understanding on various application of a novel heterocyclic subsidiary into diverse areas for new process or application. In this study, we will understand the biologically active heterocyclic compounds, biological importance of nitrogen-containing heterocyclic compounds and pyridine containing medicinal agents. The number of novel N-heterocyclic moieties with significant physiological properties and promising applications in medicinal chemistry is ever-growing. Pyrimidine is one of the most important heterocycles compounds, most potent pyrimidines used to treat of various diseases such as cancer, leukemia. Pyrimidine also represents the backbone of RNA and DNA. Key words: Heterocyclic compounds, heteroatom, nitrogen-based heterocycles, biological activities, pyrimidine, nucleosides.