Abstract: An efficient look-up table encoder for encoding k bit information words with linear error correcting block codes is provided comprising a plurality of read-only memories having 2.sup.x.sbsp.1, 2.sup.x.sbsp.2, . . . , and 2.sup.x.sbsp.i address locations, respectively, where x.sub.1 +x.sub.2 + . . . x.sub.i =k. Each of the read-only memories receives a portion of a k bit information word that serves to address a respective location therein, thereby mapping the portion of the k bit information word into an output word stored at the location. Corresponding bits of output words from the plurality of read-only memories are mod-2 summed by n-k exclusive-OR gates to generate a parity word associated with the information word. For systematic encoding, the parity word is then appended to the information word to form a codeword uniquely associated with the information word. This encoding scheme obviates look-up tables having 2.sup.k x(n-k) storage locations.