The Four Olds or the Four Old Things (Simplified Chinese: 四旧, pinyin: sì jiū) were Old Custom, Old Culture, Old Habits, and Old Ideas. One of the stated goals of the Cultural Revolution in the People's Republic of China was to bring an end to the Four Olds.

Mao Zedong called for the Four Olds to be swept away around 1967 at the beginning of the Cultural Revolution. Red Guards listened especially attentively to Mao’s call. As a result, in the early stages of the Cultural Revolution, many things tied to China’s past culture and history were destroyed. Temples were ransacked; classic works of literature were burned; paintings were torn apart; antiquities were shattered. Nor did people escape punishment. Intellectuals were targeted as personifications of the Four Olds, and sometimes they were mocked, harassed, imprisoned, tortured, or killed.

Starting in the 1990's and continuing into the 21st century, there has been a massive rebuilding effort underway to restore and rebuild cultural sites that were destroyed or damaged in the Cultural Revolution.