The LIV Legislature of the Congress of the Union met from September 1, 1988, to August 31, 1991.
32 senators and all of the representatives had been elected in the 1988 legislative elections. The representatives served three years and the senators six, continuing into the LV Legislature of the Mexican Congress.
The Chamber of Representatives had 500 legislators, elected for three-year terms with no immediate reelection. 300 representatives were elected from uninominal districts and the other 200 from party lists in each of the proportional representation (plurinominal) electoral regions.