The fractal dimension of the boundary of trabecular bone in 62 biopsies was measured on histological sections using a box-counting method implemented on a microcomputer image analysis system. The calculated fractal dimension had a mean value of 0.99 with a normal distribution. Since this value is not greater than the topological dimension, trabecular bone, when examined by light microscopy, does not have a fractal structure. Conventional Euclidean dimensions will continue to be the most useful measurements in bone histomorphometry.