The diocese of Marsico Nuovo was a Roman Catholic ecclesiastical territory in Basilicata, southern Italy, which existed until 1818.
[7] In a letter of July 599, Pope Gregory I orders Romanus, his Defensor Siciliae, to intervene in a squabble between two men "in parochia Grumentina.
The decree "Eo quod spirituales" of 12 September 1976 created a new episcopal conference in the region called "Basilicata", to which were assigned all of the dioceses that belonged to the ecclesiastical province of Potenza, including Materana and Mons Pelusii; they had formerly belonged to the episcopal conference of "Apulia".
Based on the revisions, a set of Normae was issued on 15 November 1984, which was accompanied in the next year, on 3 June 1985, by enabling legislation.
According to the agreement, the practice of having one bishop govern two separate dioceses at the same time, aeque personaliter, was abolished.
There was to be only one diocesan Tribunal, in Potenza, and likewise one seminary, one College of Consultors, and one Priests' Council.