As any code based multiple access system, the choice of code sequences in TH-UWB system is very important to minimize the effect of Multi Users Interference (MUI) and enhance the performance in terms of Bit Error Rate (BER). In this contribution we propose to highlight the inƀuence of THcodes on the performance of the system by deſning a criteria to select TH-codes then by computing the BER of correlating receiver for chaotic and classical code sequences.Index Terms-Ultra wide band communication, Time hopping, Chaotic sequences, Average of squared collision number, Multi user interference.