A method for discontinuously receiving packets in a mobile communication system and an apparatus thereof are provided to reduce a transmission delay and to prevent degradation of the service quality in a mobile communication system supporting a DRX mode. A method for discontinuously receiving packets in a mobile communication system comprises the following several steps. A terminal receives DRX(Discontinuous Reception) configuration information for an arbitrary service, signaled from a base station(505). The terminal monitors a downlink shared control channel until a packet transmitted thereto occurs(510). The terminal determines whether there is any packet transmitted thereto in the course of monitoring control information on the downlink shared control channel(515). Upon detecting a packet transmitted thereto by checking the control information, the terminal stores a reception time of the downlink shared control channel, and then receives a packet at a packet reception time allocated thereto by performing a specific HARQ(Hybrid Automatic Repeat Request) operation(520). The terminal determines whether the received packet is a DRX service packet(525). When the received packet is not a DRX service packet, the terminal initializes the stored reception time of the downlink shared control channel(530) and returns to step 510 where it continues to monitor the downlink shared control channel. When the received packet is a DRX service packet, the terminal recognizes the stored reception time of the downlink shared control channel as a starting point of the DRX cycle(535), and it performs a DRX operation(540).