Martinsburg is a city in Audrain County, Missouri, United States.

[5] According to the United States Census Bureau, the city has a total area of 0.27 square miles (0.70 km2), all land.

There were 152 housing units at an average density of 563.0 per square mile (217.4/km2).

32.8% of all households were made up of individuals, and 13.9% had someone living alone who was 65 years of age or older.

The racial makeup of the town was 98.16% White, 0.61% African American, and 1.23% from two or more races.

22.4% of all households were made up of individuals, and 11.9% had someone living alone who was 65 years of age or older.

St Joseph Elementary School in Martinsburg is a private, Roman Catholic institution.