Abstract: We present a sketch-based modeling system, inspired from anatomical drawing, which constructs plausible 3D models of branching vessels from a single sketch. The input drawing typically includes non-flat silhouettes and occluded parts. We exploit the sketching conventions used in anatomical drawings to infer depth and curvature from contour and skeleton curves extracted from the sketch. We then model the set of branching vessels as a convolution surface generated by a graph of skeleton curves: while these curves are set to fit the sketch in the front plane, non-uniform B-spline interpolation is used to give them smoothly varying depth values that meet the set of constraints. The final model is displayed using an expressive rendering method that imitates the aspect of chalk drawing. We discuss the future use of this system as a step towards the interactive teaching of anatomy.