3GPP New Radio (NR) air interface operating in a millimeter wave frequency band is expected to provide the main bearer service in the fifth generation (5G) mobile systems. Compensating for high propagation losses by using high gain antennas at both user equipment † (UE) and access point (AP) sides these systems will greatly benefit from highly directional transmission serving unicast sessions. However, highly directional nature of NR communications may affect the conventional service procedures of multicast sessions in wireless networks as more than a single transmission may be required to serve UEs in the same multicast group. Accounting for random resource requirements induced by locations of UEs as well as human blockage phenomenon, we develop a model for performance analysis of 5G NR systems serving a mixture of unicast and multicast sessions. The main performance metrics of interest are drop probabilities of unicast and multicast sessions. The proposed model, complemented with antenna models and beam-steering procedure, can be further used to determine optimal AP intersite distance for 3GPP NR systems. © 2018 IEEE.