This document analyzes the effect of seed length on the performance of an optical interleave division multiple access (IDMA) system using prime inter-leavers. It compares the bit error rate (BER) performance of prime inter-leavers with different seed lengths ranging from 2 to 13 for a fixed number of users and data length. The simulation results show that increasing the seed length from 2 to the maximum single digit prime number 7 decreases the BER significantly, with the optimal BER achieved for a seed length of 7. However, BER increases again for seed lengths in double digits. Similarly for a longer data length, the optimal BER is obtained for a seed length of 7. In conclusion, using prime inter