Some demonstrative embodiments include apparatuses, devices, systems and methods of dynamically scheduling a transmit opportunity. For example, a first wireless station may be configured to generate a grant frame including a duration field and a dynamic allocation information field, the dynamic allocation information field including an allocation duration subfield, the allocation duration subfield being set to a value within a predefined range of values, when the grant frame is to grant to a second wireless station a period after a Transmit Opportunity (TxOP), the allocation duration subfield being set to a predefined value which is not within the predefined range of values, when the grant frame is to grant to the second wireless station a period within the TxOP; and transmit the grant frame during the TxOP.