The impeachment trial of Andrew Johnson, 17th president of the United States, was held in the United States Senate and concluded with acquittal on three of eleven charges before adjourning sine die without a verdict on the remaining charges. It was the first impeachment trial of a U.S. president and was the sixth federal impeachment trial in U.S. history. The trial began March 5, 1868, and adjourned on May 26.

Andrew Johnson was an American politician who served as the 17th president of the United States from 1865 to 1869. He assumed the presidency following the assassination of Abraham Lincoln, as he was vice president at that time. Johnson was a Democrat who ran with Abraham Lincoln on the National Union Party ticket, coming to office as the Civil War concluded. He favored quick restoration of the seceded states to the Union without protection for the newly freed people who were formerly enslaved. This led to conflict with the Republican-dominated Congress, culminating in his impeachment by the House of Representatives in 1868. He was acquitted in the Senate by one vote.