An apparatus and a method for transmitting/receiving a packet in a dual modem mobile communication terminal support data communication using both a host modem and a slave modem by additionally driving the slave modem when packet traffic is heavy. In the method for transmitting/receiving, at a host modem, a packet in a mobile communication terminal that includes the host modem and a slave modem, when a packet is received under a state where only the host modem is driven, it is determined whether a buffer count of the host modem is greater than a reference value. When the buffer count of the host modem is greater than the reference value, the slave modem is additionally driven and the received packet is provided to the slave modem.