Moscovian (Middle Pennsylvanian) deposits with mixed oolitic and fossil-rich carbonates have long been known from the Kirchaou KR-1 borehole in SE Tunisia. However, its biostratigraphy has never been investigated in detail. This study is mainly dedicated to reviewing the late Bashkirian and Moscovian successions, and characterizing the late Moscovian-early Kasimovian boundary interval. The important fusulinoid faunas of the Middle Pennsylvanian interval within the 315.5-meter-thick KR-1 borehole mainly include staffellines, eostaffellines, millerellines, pseudostaffellines, and Fusulinoidea, which are first illustrated here. The distribution of the main index taxa allows us to distinguish four foraminiferal biozones: (1) the Tikhonovichiella tikhonovichi - Profusulinella Zone of the Melekessian-Vereian (latest Bashkirian-earliest Moscovian), (2) the Beedeina – Citronites Zone of the Kashirian (late early Moscovian), (3) the Taitzehoella prolibrovichi – Fusulina of the Podolskian (early late Moscovian), (4) the Protriticites - Quasifusulinoides Zone of the Myachkovian - Krevyakinian (late late Moscovian – early Kasimovian). The Moscovian - Kasimovian transition is mainly characterized by Protriticites, Quasifusulinoides, Montiparus, Topilinia, Beedeina, Fusiella, Profusulinella, and Fusulinella taxa. The study of fusulinoid assemblages allows reliable correlations with coeval associations from the Russian Platform, Southern Urals, Western Europe, Spain, and Donbas (Ukraine)