长元音是指一种持续时间较普通元音发音时较长的元音。与长元音相对的发音时较短的元音称为短元音。

国际音标对于长元音的标记方式，是在元音之后加上〈ː〉的记号。国际音标亦有半长元音的记号〈ˑ〉（即长元音记号的上半截）。

现时世上有不少语言都对长短元音作出辨别，日语是当中一个代表。此外，爱沙尼亚语的元音更细分为短、长、超长三种不同的长度。英语本来亦有对元音的长度作出区分，但现时在标准英语里已经消失，但在部份澳洲及新西兰的地方口音里仍然存在。

In linguistics, vowel length is the perceived duration of a vowel sound. Often the chroneme, or the "longness", acts like a consonant, and may have arisen from one etymologically, such as in Australian English. While not distinctive in most other dialects of English, vowel length is an important phonemic factor in many other languages, for instance in Finnish, Fijian, Japanese, Old English, and Vietnamese. It plays a phonetic role in the majority of dialects of British English, and is said to be phonemic in a few other dialects, such as Australian English, South African English and New Zealand English. It also plays a lesser phonetic role in Cantonese, unlike other varieties of Chinese.