The present investigation deals with the lithostratigraphy and planktonic foramini-feral biostatigraphy of the Shiranish Formation from a surface section in Sinjar area, northwestern Iraq. Depending on lithological characteristic, the formation is divided into three units: the lower unit consists of friable marl, the middle unit embrace an alternations of marl, marly limestone, limestone, sandy limestone and lenses of breccia, while the upper unit is consist of marl and marly limestone. The stratigraphic distribution of the planktonic foraminifera throughout the section permits the recognition of four zones, these are: 1. Globotruncanita calcarata Zone. 2. Globotruncanella havanensis – Rosita fornicata Zone. 3. Globotruncana aegyptiaca Zone. 4. Gansserina gansseri Zone, The present work indicates that Shiranish Formation is of Late Campanian-Late Maastrichtian age.