A computer program, SUBCUR, is described which permits analysis and ra
pid identification of geometrical differences and patterns of variance
between two DNA duplexes. The program is compatible with the CURVES 3
.1 package1 and allows graphical visualization of the structural diffe
rences. Examples are provided which illustrate the applicability of th
e program in analyzing the different backbone conformations of two hel
ices and the different curvatures of two helices.