Mohiuddinagar is a city located in Samastipur district of the eastern state of India, Bihar. It is in the south of Samastipur at a distance of 30 km. The Ganga River flows through the town. Mohiuddin Nagar Railway Station on the Bachwara Hajipur rail route and the Patna Airport are the nearest access points.

The Indian Census report published in 2001 states that Mohiuddinagar had a population of 13,764. Males` account for 52% of the population and females comprises of the remaining 48%. In Mohiuddinagar, 21% of the population is less than six years of age. The Census report also throws light on the literacy rate of the town, which provides data about the status of the population. The average literacy rate of Mohiuddinagar is 44%, which is much lower than the national average literacy rate, which is 59.5%. To be specific, the male literacy rate is 52% and the female literacy rate of Mohiuddinagar is 35%.