There has been an enormous development in peptide chemistry with regard not only to the isolation, synthesis, structure identification, and elucidation of the mode of action of peptides, but also to their applications as tools in the life sciences. Peptides have been of interest in biochemistry, chemistry, biology, pharmacology, medicinal chemistry, biotechnology, and gene technology. These important natural products have a broad range with in point of their complexity. Since different amino acids are connected via peptide bonds to produce a peptide or a protein, a number of different sequences are possible–depending on the different building blocks and length of the peptide. As all peptides display a high degree of conformational diversity, it follows that many diverse and highly specific structures can be observed. Although many researches have dealt with the synthetic aspects of peptide chemistry, this review covers its biological applications of peptide based molecules.