With the advent of the lighting revolution, solid-state light sources represented by gallium nitride (GaN)-based light-emitting diodes (LEDs) are gradually replacing traditional light sources, appearing in every corner of industry and daily life. However, some long-standing basic scientific problems, such as the quantum-confined Stark effect, Droop effect, etc., have lowered the performance of (0001) polar GaN-based LEDs, especially for those in the yellow and red bands. LED structures grown in nonpolar or semipolar directions can effectively avoid or reduce the negative effects of the internal electric field. It provides an effective method to cover the green gap and to achieve a full visible light spectrum. However, similar to the polar direction, nonpolar/semipolar orientations also lack a suitable substrate, which leads to a number of challenges for the heteroepitaxial nonpolar/semipolar nitrides. This chapter introduces the difficulties and corresponding solutions for the epitaxial nonpolar/semipolar nitrides on silicon substrates and sapphire substrates, especially for the epitaxy on patterned substrates. The anisotropic structural and optical properties are also presented, which are different from the traditional polar orientation.