Diffusion tensor imaging (DTI) can provide the directionality of water diffusion in tissues, informing on its underlying microstructures and microdynamics. There has been no previous report on the visualization of anterior portion of the longitudinal anal muscle (aLAM). In this case study, we present the 3D visualization of the aLAM in normal male subjects with DTI. By adjusted parameters for DTI sequence, we could successfully visualize thin smooth muscle layer of the rectum. This technique could be useful when planning operation for rectal and anal diseases.