This paper presents a design of syndrome computation block for Reed-Solomon decoder for RS (255, 239) code. For calculating the syndromes, three-parallel processing has been used. Parallelizing allow inputs to be received at very high rates and outputs to be delivered at correspondingly high rates with minimum delay. RS (255, 239) code consists of 255 symbols which are multiple of 3. So three symbols are inputted parallely in syndrome computation block. This process can be adapted in the FEC devices.