We conducted a user study evaluating five selection techniques for augmented reality in optical see-through head-mounted displays (OST-HMDs). The techniques we studied aim at supporting mobile usage scenarios where the devices do not need external tracking tools or special environments, and therefore we selected techniques that rely solely on tracking technologies built into conventional commercially available OST-HMDs [i.e. gesture trackers, gaze tracking and inertial measurement units (IMUs)]. While two techniques are based on raycasting using built-in IMU sensing, three techniques are based on a hand-controlled 3D cursor using gestural tracking. We compared these techniques in an experiment with 12 participants. Our results show that raycasting using head orientation (i.e. IMU on the headset) was the fastest, fatigueless and the most preferable technique to select spatially arranged objects. We discuss the implications of our findings for design of interaction techniques in mobile OST-HMDs.