This disclosure describes techniques for constraining depth intra mode coding in a three-dimensional (3D) video coding process, such as 3D-High Efficiency Video Coding (3D-HEVC). In some examples, the techniques for constraining depth intra mode coding may prevent transform tree nodes from being split into sub-transform tree nodes when a depth prediction unit that corresponds to the transform tree node is predicted according to a depth modeling mode (DMM). In further examples, the techniques for constraining depth intra mode coding may prevent the DMM mode from being used when the maximum transform unit size that corresponds to a depth prediction unit is greater than the size of the depth prediction unit. The techniques for constraining depth intra mode coding may prevent characteristics of the DMM prediction modes used in 3D-HEVC and characteristics of the transform tree subdivision used in 3D-HEVC from interfering with each other.