A method and apparatus for enhanced uplink multiplexing are disclosed. A set of combinations of MAC-d flows (and/or logical channels) that are allowed to be multiplexed within a MAC-e PDU is defined for a WTRU. The WTRU MAC-e entity selects a combination among a set of allowed combinations for multiplexing MAC-d flows for each MAC-e PDU. Certain MAC-d flow combinations may be defined that can not be blocked from transmission even when the WTRU is in a transmit power restricted state. The amount of data from each logical channel or corresponding MAC-d flow that can be multiplexed within a MAC-e PDU may be defined to ensure guaranteed data rates. When the WTRU is in a restricted power condition, an indication of the restricted power condition may be passed to the Node-B with the EU transmission.