Northern Khmer, also called Khmer Surin, is the dialect of the Khmer language spoken by the Khmer native to the Thai provinces of Surin, Sisaket, Buriram and Roi Et as well as those that have migrated from this region into Cambodia.

Northern Khmer differs from the Phnom Penh dialect (considered the standard) in the number and variety of vowel phonemes, consonantal distribution, lexicon and grammar, giving Northern Khmer a distinct accent easily recognizable by speakers of other dialects. Some speakers of Northern Khmer may understand other varieties of Khmer but speakers of standard Khmer who have not been exposed to Northern Khmer often have trouble understanding Northern Khmer. These facts have led some linguists to advocate considering Northern Khmer a separate, but closely related language.