This thesis investigates the design and realization of integrated planar antennas for millimeter-wave applications. The state-of-the-art antenna integration and packaging technologies are extensively studied, and an antenna design flow is proposed. A number of integrated antenna designs by applying different integration approaches and technologies, i.e. on printed circuit board (PCB), on-chip and in Benzocyclobutene (BCB) above-wafer process, are presented. The designs target not only high performance, but also the practical considerations of low-cost, feasibility, better reliability, and good reproducibility. They cover the industrial, medical, and scientific (ISM) bands of 60 GHz, 122 GHz, and 245 GHz with outstanding performance in a low-cost fashion by applying innovative, appropriate integration methods and sophisticated design. From the presented results of the thesis it is feasible to realize high performance integrated planar antennas in the entire millimeter-wave range and beyond in a cost-effective fashion.