The data include nannofossil assemblages from the Cenomanian-Turonian boundary of the Smoky Hollow (SH#1) core in south central Utah. For assemblage studies, slides were made from more dilute solutions so that counts could be conducted. Nannofossil specimens were observed under a Carl Zeiss Axioskop 2 Plus light microscope at a magnification of 1000x and identified using standard taxonomy as described by Perch-Nielsen et al. (1985). Specimens one-half the size of a coccolith or larger were identified and a total of over 31,000 specimens were counted.