A method and apparatus of performing discontinuous reception (DRX) and downlink inter-frequency and inter-radio access technology (RAT) measurements in CELL_FACH state are disclosed. While in DRX mode, a wireless transmit/receive unit (WTRU) may perform inter-frequency and inter-RAT measurements in a measurement occasion that fall into a DRX period. The WTRU may perform the measurements while T321 timer is running. The WTRU may take the measurements on first predetermined number of frame in which a DRX frame would coincide after a last reception frame if DRX operation was ongoing. The WTRU may periodically wake up for downlink reception in CELL_FACH state in accordance with a common DRX pattern that is common to all WTRUs in a cell or may wake up from DRX upon reception of the order and receiving a common traffic.