We propose a short-period dispersion-managed fiber that consisted of conventional single-mode fiber (17 ps/km/nm) and negative dispersion fiber (-15 ps/km/nm), Thus, the average dispersion of the proposed fiber was only 1 ps/km/mn, The lengths of the positive and negative liber sections were only 4.5 km so that they can be accommodated within a single 9-km-long cable. We evaluated the performance of this fiber using a 320-Gb/s (32 x 10 Gb/s) WDM system with 50-GHz channel spacing. After 564-km transmission, the average Q-factor was measured to be better than 18 dB without any dispersion compensation.