There are some exceptions to the rules of vowel harmony.

Several languages of the region have 8- or 9-vowel systems with some form of vowel harmony.

There are also other traces of vowel harmony in Korean.

The Samic languages show no evidence for original vowel harmony.

The Korean language of this period had vowel harmony to a greater extent than it does today.

For more discussion, see the article on vowel harmony.

The Korean language of the 15th century had vowel harmony to a greater extent than it does today.

At least two parameters were used in their design, vowel harmony and iotation.

There is also a process of vowel harmony in strings longer than a word, known as "harmonic groups".

Unlike many others, they do not have vowel harmony.