This article presents a hybrid approach to smooth surface reconstruction from serial cross sections, where the number of contours varies from section to section. In a triangular surface-based approach taken in most reconstruction methods, a triangular surface is constructed by stitching triangular patches over a triangular net generated from the compiled contours. In the proposed approach, the resulting surface is a G1 composite surface consisting of three kinds of surfaces: skinned, branched, and capped surfaces. Each skinned surface is first represented by a B-spline surface approximating the serial contours of the skinned region and then is transformed into a mesh of rectangular Bezier patches. On branched and capped regions, triangular G1 surfaces are constructed such that the connections between the triangular surfaces and their neighbouring surfaces are G1 continuous. Because each skinned region is represented by an approximated rectangular C2 surface instead of an interpolated triangular G1 surface, the proposed approach can provide more visually pleasing surfaces and realize more efficient data reduction than the triangular surface-based approach. Some experimental results demonstrate its usefulness and quality.