Biomarkers provide a dynamic and powerful approach to understanding the spectrum of disease with applications in observational and analytic epidemiology, randomized clinical trials, screening, diagnosis and prognosis. Biomarker is defined as alteration in the constituents of tissues or body fluids, these markers offer the means for homogeneous classification of a disease and risk factors, and then can extend our base information about the underlying pathogenesis of disease. A prerequisite for the clinical use of biomarker is elucidation of the specific indication, standardization of analytical methods, characterization of analytical features, incremental yield of different markers for given clinical indications. Biomarkers can also reflect the entire spectrum of disease from the earliest manifestations to the terminal stages. The major use of biomarkers has been employed  in clinical investigation. The article features biomarkers in drug development and in disease diagnosis.