The L Legislature of the Congress of the Union met from 1976 to 1979. This 50th session of Congress consisted of senators and deputies who were members of their respective chambers. They began their duties on September 1, 1976, and ended on August 31, 1979.
The senators and deputies were elected to office in the 1976 Mexican general election. The senators were elected for a period of six years (so they maintained their seat in the next legislature), and the deputies were elected for a period of three years.