Abstract. Steganography is the art and science of embedding secret data in another medium to prevent the leakage of secret information. A VQ-based (vector quantization) steganographic method usually involves changes of the block values in the VQ images, which might cause serious distortion. As a result, many existing methods use closest pairs or clustering techniques to preserve an acceptable image quality. In this paper, we propose a new VQ steganographic method for preserving extremely high image quality. Instead of finding similar pairs, the proposed method uses a pair of dissimilar codewords to embed one secret bit in each image block. The property of dissimilar pairs allows the VQ image to be nearly fully recovered after extraction of the secret bits. Experimental results show that our method keeps an acceptable embedding capacity but has much better image quality than existing schemes.