In the 1873 Iowa State Senate elections, Iowa voters elected state senators to serve in the fifteenth Iowa General Assembly. Elections were held in 23 of the state senate's 50 districts. State senators serve four-year terms in the Iowa State Senate.

The general election took place on October 14, 1873.

Following the previous election, Republicans had control of the Iowa Senate with 42 seats to Democrats' eight seats.

To claim control of the chamber from Republicans, the Democrats needed to net 18 Senate seats.

Republicans maintained control of the Iowa State Senate following the 1873 general election with the balance of power shifting to Republicans holding 36 seats, Democrats having 10 seats, and four Anti-Monopoly members (a net gain of 2 seats for Democrats and 4 seats for the Anti-Monopoly Party).

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District boundaries in the Iowa Senate were redrawn before the 1873 general election.