We experimentally demonstrate the multiband orthogonal frequency-division multiplexing ultra-wideband (MB-OFDM UWB) over fiber system with direct detection. Different sub-carrier modulation formats (quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (QAM)) are investigated in the MB-OFDM UWB over fiber system. The experimental results show that a 3.84 Gb/s 16 QAM-encoded MB-OFDM UWB signal can be successfully transmitted over 70 km standard single-mode fiber without chromatic dispersion compensation.