A method and apparatus for uplink transmission is disclosed. A wireless transmit/receive unit (WTRU) transmits, to a Node-B, a first type message, a second type message, and a third type message. The first type message indicates that the WTRU has uplink buffered data available for transmission. The second type message includes a plurality of indications, wherein each indication indicates an amount of uplink buffered data associated with at least one priority. The third type message indicates an amount of uplink buffered data and has less information than the second type message. The WTRU receives, in response to the transmitted first type message, the transmitted second type message, or the transmitted third type message, an uplink data scheduling message. The WTRU transmits uplink data over an uplink channel based on the received uplink data scheduling message.