A method and apparatus for enhanced uplink (EU) dedicated channel data transmission. On a condition that a scheduling message is not available, wherein the scheduling message is for scheduling scheduled data transmission, a wireless transmit/receive unit (WTRU) transmits non-scheduled data up to a threshold amount of data in absence of the scheduling message. On a condition that scheduled data for a logical channel is in an EU data buffer of the WTRU, the WTRU transmits EU scheduling information with EU non-scheduled data transmission in absence of the scheduling message, wherein the scheduling information indicates a total amount of data in the EU data buffer and an amount of EU data buffered for a priority logical channel. The WTRU receives a scheduling message in response to the transmitted EU scheduling information and transmits the scheduled data in response to the scheduling message.