Mount Lena is a census-designated place (CDP) in Washington County, Maryland, United States.

According to the United States Census Bureau, the CDP has a total area of 1.2 square miles (3.1 km2), all land.

There were 212 housing units at an average density of 170.5 per square mile (65.8/km2).

19.1% of all households were made up of individuals, and 10.6% had someone living alone who was 65 years of age or older.

None of the families and 1.9% of the population were living below the poverty line, including no under eighteens and 12.0% of those over 64.