Some advantages of meshing Wireless Personal Area Networks (WPAN) are to increase the network coverage without high transmission power, self-configuration and self-healing, increased route redundancy and fewer retransmissions. This paper discusses the capacity issues when meshing high data rate WPANs i.e. IEEE 802.15.3, IEEE 802.15.3a and IEEE 802.15.3c. The capacity bottlenecks are discussed which arise in multihop communication with a shared superframe. The paper provides detailed analysis on the superframe capacity using different transmitter data rates and highlights the importance of frame aggregation to achieve higher throughput and low overhead. The paper concludes by discussing possible approaches to improve the capacity of meshed WPANs.