Ultra wideband (UWB) technology is one of the promising solutions for future short-range communication which has recently received a great attention by many researchers. So far, two standards have been proposed to the IEEE 802.15.3a task group (TG3a) as a high-speed physical technology for next-generation wireless personal area networks (WPAN). These technologies are multiband orthogonal frequency division multiplexing (MB-OFDM) UWB and direct-sequence (DS) UWB; two incompatible standards which, due to the withdrawal of the standardization process, will have to coexist in the near future. In this paper, we present a performance analysis of MB-OFDM UWB communication in the presence of binary phase shift keying time-hopping (BPSK-TH) UWB and BPSK-DS UWB interfering transmissions. In the bit error rate (BER) analysis, it is considered that there are multiple UWB interferers affecting the MB-OFDM signal. A Gaussian approximation is considered for the multiple UWB interferers under consideration, and the BER performance is evaluated for a multiband OFDM UWB system and the WLAN 802.11a singleband OFDM-based standard. Numerical results and comparisons are provided for different OFDM and UWB coexisting systems.