We fabricated highly aligned porous silicon carbide (SiC) ceramics decorated with SiC nanowires by the unidirectional freeze casting of SiC/camphene slurries with various polycarbosilane (PCS) contents, ranging from 0 to 20 wt% in relation to the SiC powders, in which the PCS preceramic was used as a binder and source for the in situ growth of the SiC nanowires. In this method, aligned pore channels were formed as a replica of the unidirectionally grown camphene dendrites, while SiC nanowires were formed within the pores in situ via a vapor-liquid-solid (VLS) mechanism during the heat treatment of the porous green bodies at 1400 degrees C for 1 h in a flowing Ar atmosphere. The pore channels were well decorated with single-crystalline SiC nanowires. It was also observed that the growth of the SiC nanowires was strongly affected by the initial PCS content and heat-treatment temperature.