A by-election was held on 29 August 2020 for the seat of Slim in the Perak State Legislative Assembly. The seat fell vacant following the sudden death of the incumbent Member of the Legislative Assembly (MLA) from United Malays National Organisation (UMNO) of the Barisan Nasional (BN) coalition, Mohd. Khusairi Abdul Talib, 59, due to a heart attack on 15 July 2020. He had held the seat for four terms since 2004. The Election Commission (EC) had set the nomination day on 15 August 2020, early voting on 25 August and polling day for 29 August with a 14-day campaign period.