Problem statement:The objective of this study particularly aims the static segmentation of the lips. Approach: For that, we proposed algorithms for the determination of certain characteristic points of the lips, as well as a method of optimal slope allowing to trace the cubic ones forming external contours of the lips. Results: Finally to make sure of the performance of our algorithms, we also used a manual determination of the characteristic points. Conclusion: The results obtained showed the rigor of our algorithms and that by comparing the results obtained by the manual determination with those of the semi-automatic determination.