Zhuyin fuhao (simplified Chinese: 注音符号; traditional Chinese: 注音符號; pinyin: Zhùyīn fúhào; Zhuyin Fuhao: ㄓㄨˋ ㄧㄣ ㄈㄨˊ ㄏㄠˋ; literally "phonetic symbol"), often abbreviated as zhuyin and colloquially called bopomofo, is a phonetic system for transcribing Chinese, especially Mandarin. It was introduced in the 1910s.

Consisting of 37 characters and four tone marks, it transcribes all possible sounds in Mandarin. Although phased out in Mainland China in the 1950s, this system is still widely used as an educational tool and Chinese computer input method in Taiwan.

Zhuyin is often called bopomofo which is derived from the names of the first four characters of the system (ㄅㄆㄇㄈ) and occasionally used to refer to pinyin in mainland China. In official documents, it is occasionally called the "Mandarin Phonetic Symbols I" (國語注音符號第一式), abbreviated as the "MPS I" (注音一式).

In English translations, the system is often called either Chu-yin or the Mandarin Phonetic Symbols. A romanized version of bopomofo, released in 1984, is called MPS II.