An apparatus and method for transmitting/receiving control information using a pilot pattern inserted in a plot field of a dedicated physical channel in a mobile communication system including a transmitter for transmitting data and a receiver for receiving the data. The apparatus and method include selecting control information according to whether the data is received; and selecting a pilot pattern according to the control information, and inserting the selected pilot pattern in a pilot field of a dedicated physical channel as the control information, before transmission. The pilot pattern includes a first pilot pattern used when the control information is not transmitted, a second pilot pattern being orthogonal with the first pilot pattern, and a third pilot pattern generated by inverting a sign of the second pilot pattern.