Recursion has often been studied in healthy subjects who have no impairment of their language organs. This chapter presents the neural sites of recursion and examines whether recursion still plays a relevant role in aphasic patients, who show an impoverishment of spoken language. Recursion is found to play a relevant role in mental language, even if its externalisation is deficient. Finally, two topical issues are addressed. The first concerns the denial of recursion as a defining property of human language, since some languages, such as Pirahã, seem to lack it, and the second addresses whether artificial generative intelligences can produce or recognise sentences that include recursive patterns.