Children who suffer from brain disorders, either disorders due to medical factors or disorders due to abnormalities in brain function also pass through the language acquisition stage. KY is a teenager who has a language disorder and is declared mentally retarded. Children with mental retardation acquire language skills in essentially the same way as non- mentally retarded children. Their rate of acquiring language skills was lower than that of non-mindset children of the same mental age. In the case of Kartini, Kartini was able to pronounce the sounds [a], [c], [d], [e], [g], [h], [i], [j], [k], [l], [s], [t], [u], and [y]. There are some consonants that cannot be pronounced if the consonants are at the beginning, in the middle and at the end. For vocals [u] Kartini can pronounce it but it is not perfect. The tongue is located between the oral cavity under the palate. For consonant [i] Kartini sometimes changes it to vowel [e]. Consonants [b], [d], [m],[t] are sometimes missing. For the consonant [n] which is located at the end of the word, Kartini changes it to the sound [ŋ]. However, for the consonant [n] which is located in the middle of the word Kartini omitted it. For consonant [s] Kartini undergoes obliteration and replacement. Consonant [s] changes to consonant [c] , Consonant [s] at the end of the word changes to consonant [t].