Introduction A number of acquisition and reconstruction techniques have recently been proposed to extract the orientations of the white matter fibres within each imaging voxel from diffusion-weighted imaging (DWI) data. Of these, the diffusion tensor model is currently the most commonly used, but is limited in that it cannot resolve crossing fibres [1]. Constrained spherical deconvolution (CSD) has recently been proposed to address this problem [2]. However, the method has only been assessed using simulations. In this study, we present a validation of CSD using real phantom data, and compare the results with those obtained using Q-Ball Imaging (QBI) [1], a well-known method for resolving crossing fibres that has recently been validated using a phantom for a 90o fibre crossing [3]. However, white matter fibres will not in general intersect at 90o, and fibre-resolving techniques may prove unreliable for other angles, as suggested in a recent simulation study [4]. We therefore present results obtained using a phantom model of fibres crossing at 45o.