Over the last decade, many advancements have been made in the field of wireless communications. Among the major technology enablers being explored for the fifth-generation (5G) networks at the physical layer (PHY), a great deal of attention has been focused on millimeter-wave (mmWave) communications, massive multiple-input multiple-output (MIMO) antenna systems and beamforming techniques. These enablers bring to the forefront great opportunities for enhancing the performance of 5G and beyond-5G networks, concerning throughput, spectral efficiency, energy efficiency, latency, and reliability. At the meantime, the wireless communication is prone to information leakage to the unintended nodes due to its open nature. Hence, the secure communication is becoming more critical in the wireless networks. To address this challenge, the concept of Physical Layer Security (PLS) is explored. In this thesis, we examine the statistical mmWave transmission through linear beamforming techniques for PLS based systems. We propose the secure multiuser (MU) MIMO mmWave communications by employing hybrid beamforming at the base stations (BS), legitimate users and eavesdroppers. Using a 3 Dimensional mmWave channel model for each node, we employ the artificial noise (AN) beamforming to jam the channels of eavesdroppers and to enhance the secrecy capacity of the overall communication system. We investigate the secrecy performance on different scenarios including the single cell and multicell mmWave MU-MIMO downlink communications and reveal the key points directly related to the system security.