The purpose of this article is to show some changes that occurred in the phonological plan in the earliest stage of the evolution of Portuguese or even earlier (in Vulgar Latin), and reappeared later in the evolution of the same language. These cyclical changes are: the evolution of liquid consonants /ɾ/ and /l/, the lenition of voiced occlusives /b/, /d/ and /g/, the disappearance of the sibilant /s/ in syllabic coda and the disappearance of the nasal occlusive /n/ in intervocalic position.
These phenomena are related to identical or similar processes that have occured in other Romance languages.