Integral transformations are presented for determining structure functions of the maximum cross-section of infinitely long cylinders in terms of the structure functions of the cylinder. This includes the determination of the chord length distribution density (CLD) P(x) of the plane cross-section figure of the cylinder. P(x) is completely defined in terms of the first derivative A'(r) of the chord length distribution density A(r) of the three-dimensional rod. The general result is exemplified for the case of a triangular rod. (C) 2003 Elsevier B.V. All rights reserved.