Background in music psychology The development of singing involves not only the acquisition of melodies and words but also precise attunement to the timing structure and melodic features given by the social environment, which leads to a considerable conventionalization of performance. Background in linguistics In the course of language development, children adapt their phonetic output to the sound patterns of the target language. In singing songs, the rendition of the lyrics naturally leans on these native language sound patterns, even if the semantic content of the lyrics plays little role. Aims We report a long-term study of a child with infantile autism and severe mental handicap who sings songs but has no language. The only aspect of speech she produces is the phonetic realization of the songs she sings. This exceptional case in which musical development is dissociated from language development bears relevance to the question of the interrelationship of singing and speaking. Method The material consists of two hours of audio data or 269 reproductions of familiar songs extracted from a long-term video documentation of the single case covering the period from age 3–15. Based on phonetic and musical transcriptions, the girl's musical abilities were qualitatively assessed by expert rating. Her phonetic repertoire was quantitatively assessed. Her vocal production (phonetic and musical) was examined longitudinally with respect to its approximation to the original songs. Results At three years the autistic girl displays precocious musical competence in singing, which, however, does not grow further from this initial level. Musical creativity and expressiveness grow to a peak in middle childhood and then decline again in adolescence. The girl's phonetic inventory of sounds is highly restricted and shows no progression, but her articulation grows more and more deliberate and, within her bounds, nearer to the original words. The non-verbal girl apparently has a mental representation of the lyrics. Conclusion Musical competence, creativity and expressiveness in singing can reach a high level even in the total absence of language, and by singing, some residual language-like capacity like articulatory control may be enhanced.