Sarairanjan Assembly constituency is an assembly constituency in Samastipur district in the Indian state of Bihar.

As per Delimitation of Parliamentary and Assembly constituencies Order, 2008, No.

136 Sarairanjan Assembly constituency is composed of the following: Sarairanjan and Vidyapati Nagar community development blocks.

[1] Sarairanjan Assembly constituency is part of No.

22 Ujiarpur (Lok Sabha constituency).