In situ atomic force microscopy was utilized to study the relation between crystal structure. surface morphology. and growth mechanisins of faces of macromolecular crystals that have screw axes perpendicular to them. It was found that the {0 0 1} faces of orthorhornbic catalase. trigonal trypsin, and tetragonal Bence-Jones protein (BJP) crystals grow by successive deposition of n alternating. symmetry-related layers with a thickness of d(00n) = 1/n\c\ . These lavers are associated with two-. three- and four-fold screw-axes in the crystal structure of catalase (n - 2). trypsin (n - 3) and BJP (n - 4) crystals. respectively. Implications for growth rates and three- dimensional morphological development are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.