For example, an EDMG initiator STA of an asymmetric beamforming training may be configured to, during a Beacon Transmission Interval (BTI) in a Beacon Interval (BI), transmit a beacon via a sector of the EDMG initiator STA, the beacon including allocation information to allocate a beamforming training allocation for asymmetric beamforming training of the sector during a Data Transfer Interval (DTI) in the BI after the BTI, the beacon including one or more Receive Training (TRN-R) subfields for the asymmetric beamforming training of the sector; during the beamforming training allocation, to listen on the sector for one or more Sector Sweep (SSW) frames from one or more EDMG responder STAs; and, during the beamforming training allocation, to transmit via the sector a sector acknowledgement (ACK) frame including information based on the one or more SSW frames.