In this paper the impact of ultra wideband (UWB) interference on IEEE802.11b WLAN performance is studied through experimental tests. Extremely high power UWB transmitters, that are not FCC compliant, were used in the tests to simulate the impact of very high UWB device concentration. The measurement setup was organized to allow the UWB transmitters to generate as much interference to the WLAN network as possible. Configurations were examined with various distances between the UWB transmitters and WLAN receiver. Peer-to-peer connection and link via access point were studied in office environment during the regular office hours. The results showed that the UWB population corresponding thousands of FCC compatible devices will decrease the netw...