A novel concept for a holographic antenna-in-package (AiP) is presented enabling the seamless integration of high gain antennas at millimeter wave frequencies. The antenna is based on a holographic impedance approach stimulating a leaky wave mode at 150 GHz. Since the antenna structure is placed on top of the glass package, a large antenna aperture with high angular beam width and efficiency were achieved. The surface wave launcher (SWL) of the antenna connected to the integrated active circuitry is designed in a very compact fashion using a vertical through-glass-via (TGV) and solder balls. The performance of the proposed holographic antenna package has been investigated by an analytic model and full wave simulations. The measurement results of the antenna prototype on glass using anisotropic unit cells show excellent agreement to the simulated values. A maximum gain of 24.7 dBi, a sidelobe level of 15 dB, and a 3 dB-beam width of 4.7 • are achieved. The measured 3D-radiation pattern shows a highly directive pattern in all cuts.