White matter tractogarphy is a non-invasive method for reconstructing three dimensional fibre pathways of the brain. Several fibre tracking algorithms have been proposed for this purpose. To evaluate and compare these algorithms, it is required to use synthetic datasets for which the simulated pathways are known to the user. This paper describes an algorithm designed in Matlab to simulate a diffusion tensor digital phantom for evaluating white matter fibre tractography algorithms and assessing their ability to detect fibre crossing. This digital phantom allows quantitative assessment of the robustness of fibre tracking algorithms by varying the thickness, the angles between crossing fibres, the Fractional Anisotropy ( FA) value of synthetic paths, and background.