We propose in this paper a new algorithm for estimating the synchronization parameters (frequency offsets and delays) of multiple users in a MC-CDMA system targeted for broadband LMDS applications. The proposed algorithm exploits the code properties in the frequency domain to perform delay estimation, whereas it is based on the insertion of an appropriate header sequence to estimate the frequency offset in the time domain. Simulation results show that the algorithm obtains accurate estimates with modest computational complexity, and is robust to the presence of multiple-access interference.