Following the tremendous evolution of transferring images through the Internet, it is necessary to ensure security during this act, especially for medical images. The application of multiple watermarking tech- nique represents a solution to preserve the security of such data on the one hand, and the traceability of medical diagnoses made by doctors on the other hand. This falls under the remote collaborative work. This technique is applied in the TeNeCi (Collaborative tele-neurology) platform. The project allows practitioners to distribute the analyses of the medical images. In fact, we used the multiple watermarking technique in a wavelet field. The theory underlying this technique is to hide information in the medical image and at the same time to ensure its imperceptibility. The diagnosis made by the practitioner is the data inserted in the image. The fundamental challenge of this paper is how to hide the total diagnoses of each practitioner in the image ensuring a good quality of the image at the same time.