The 1964 Iowa State Senate elections took place as part of the biennial 1964 United States elections. Iowa voters elected state senators in 39 of the state senate's 59 districts. At that time, the Iowa Senate still had several multi-member districts. State senators serve four-year terms in the Iowa State Senate. The primary election on June 1, 1964 determined which candidates appeared on the November 3, 1964 general election ballot. Following the previous election, Republicans had control of the Iowa state Senate with 38 seats to Democrats' 12 seats.