A signal detection method and apparatus in a receiver in a MIMO mobile communication system. The receiver orders symbol combinations transmittable from a transmitter in an ascending order of the difference between the symbol combinations and transmit symbols produced by eliminating inter-symbol interference from a received signal, initializes a symbol combination with the minimum difference to an ML solution, calculates the distance between a first symbol combination and the transmit symbols and the cost of a second symbol combination, detects a symbol combination having a distance to the transmit symbols equal to the distance between the first symbol combination and the transmit symbols, and having a minimum distance, and decides the first symbol combination as the ML solution if the minimum distance exceeds the distance between the first symbol combination and the transmit symbols.