In this study, we examine the effect of spreading sequence matched filtering on the power parameters of ultrawideband (UWB) multiuser interference (MUI) under different multiple access (MA) scenarios. In many applications, a UWB receiver averages the received signal over multiple pulse transmissions to increase the signal-to-noise ratio. This can be done by employing a spreading sequence matched filter (MF). We investigate the manner in which the length of the sequence MF affects the average power, peak power, and the peak-to-average ratio (PAR) of the matched filtered version of an MUI signal. The analysis and simulation results show that each parameter changes with the number of averages in a different manner, depending on the MA scenarios. This difference is particularly remarkable with regard to the PAR. The results of the analysis performed for a simplified scenario are supported by the simulation results obtained for a realistic multipath environment.