A signature opening apparatus for receiving one signature at a time from a source of signatures fed to the apparatus in a steady stream. The apparatus includes an opening drum mounted for rotation on a shaft for delivering opened signatures to a continuous signature carrying chain. It utilizes at least one gripper assembly mounted for rotation with the opening drum for opening one signature at a time. The apparatus also includes a timing mechanism to allow the gripper assembly to initiate gripping of signatures at a first preselected point, to fully grip signatures at a second preselected point and to release signatures at a third preselected point. The gripper assembly includes an elongated countinuously curved finger having a first end mounted for rotation relative to the opening drum and a second end normally projecting beyond the opening drum. The apparatus also includes a seat as a part of the gripper assembly to be engaged by the second end of the finger. The gripper assembly is formed with the finger having a continuously curved inner surface and a continuously curved outer surface. It utilizes the timing mechanism to allow the finger to rotate from a position where the second end normally projects beyond the opening drum in spaced relation to the seat to a position where the second end cooperates with the seat to grip signatures therebetween. Additionally, the apparatus utilizes a mechanism for rotating the finger back to the position where the second end of the finger normally engages the seat.