Summary: The use of concatenated codes in non-coherent synchronous optical fiber CDMA networks is proposed. The concatenated code sequences are generated using Walsh code sequences and balanced Walsh code sequences, which are selected from Walsh code sequences. The selection of balanced Walsh code sequences is presented and the design of fully programmable electro-optical transmitter and receiver is reported. In the proposed network, sequence-inversion keying of intensity modulated unipolar concatenated code sequences is employed at the transmitter and unipolar-bipolar correlation is implemented at the receiver. The analysis of the system BER performance is presented and it is proved that multiple-access interference is completely eliminated. It is also shown that the BER performance of the proposed system is better than that of non-coherent synchronous optical fiber CDMA system using optical orthogonal codes with double hard-limiters.