For this study, corrosion inhibition role of expired Doxercalciferol drug was studied on the mild steel (MS) corrosion in 3 M HCl medium at 333 K by electrochemical (Tafel curves and AC impedance spectroscopy), atomic absorption and scanning electron microscopy techniques. Tafel plot studies confirm that, the corrosion inhibition property of expired Doxercalciferol drug is of mixed type. The impedance study proves that, the corrosion inhibition property enhanced with increase in the expired Doxercalciferol drug concentration. The atomic absorption spectroscopy and scanning electron microscopy (SEM) results fully supports the adsorption of electron rich elements of expired Doxercalciferol drug on the MS surface in 3 M HCl medium.