The latest Cretaceous (Maastrichtian) to Middle Eocene (Lutetian) interval of shallow water carbonate rocks in the NE part of the Arabian Pensinsula (Oman Mountains) includes important regional oil reservoir units. These carbonates are richly fossiliferous in foraminifera, which have been useful in correlating sequences and formations. Previous foraminiferal studies have indicated the existence of several hiatuses or lacunae related to sea level changes or due to erosion. Subsequent studies of the abundant calcareous nannofossils have permitted definition of these hiatuses via high resolution biostratigraphy. However, these previous studies were of limited extent. In this study a total of 103 nannofossil species were identified from the upper Maastrichtian–Lutetian successions at Jabal Qarn El Barr, El Faiyah Range Mountains (Jabal Thanays and western side of Jabal Buhays), United Arab Emirates, as well as Jabal El Rawdah, west of the Northern Oman Mountains, Oman.