In respect to the issues on privacy, security and legal significance of a document, some sorts of security protections should be put on a document to ensure its genuineness and integrity. In this research, signatories' biometric fingerprint in digital binary format as a watermark message will be embedded into a gray level document image by discrete wavelet transform. Experimental results show that the proposed method is quite robust to various attacks such as Gaussian White oise, JPEG Compression and Low-Pass Filters, and is successfully tested for embedding the fingerprint watermark message and extraction even if the watermarked document image has been attacked by some imitated interferences. In our prototype system, Discrete Wavelet Transform method can be applied to authenticate the genuine against signatories by comparing signatory's fingerprint with the fingerprint watermark message extracted from the archived watermarked document image. © 2009 IEEE.