The infinitive sentences may be, in Sardinian, out of the main clause verb-government. The infinitive, in the Logudorese diatopic variety, can have, but not necessarily has, the features of agreement with the subject, while in Campidanese diatopic variety these features are absent. That is because the infinitives in Sardinian are oscillating in respect to the infl parameter, which assigns the value "+" or "-" to the realization that allows free choice of [± tense] in an Inflection having the features of agreement. The Subject of these infinitives is always placed at the end of the sentence, and, anyway, after the infinitive verb. These Sardinian infinitives have different points of contact and similarity with the Portuguese infinitives, but also deep differences. The aim of his article is to examine all this facts, and to identify the different types of infinitive construction in Sardinian.