B'nai Jacob Synagogue is a historic Conservative synagogue located at the intersection of Nissley and Water Streets, Middletown, Dauphin County, Pennsylvania, in the United States.

It was built in 1906, and is a one-story brick building with a front gabled roof.

Atop the front gable is a Star of David.

It is the oldest building erected as a synagogue in Dauphin County.

[2][3] It was added to the National Register of Historic Places in 1985.