Point defects in semiconductors play a fundamental role for the material properties. Dopants like impurities forming shallow donors and acceptors provide the means of controlling the electrical conductivity of the material, which is the basis of many applications in devices. Native defects like vacancies and interstitial atoms, and their combination with impurities introduce, mostly unwanted deep levels in the bandgap, and thus may serve as traps or recombination centers for the carriers. Some of these defects are introduced during the growth of the material, others by the processing steps necessary in the device production. In this chapter, we present current knowledge about point defects in the III-nitrides based on recent works, both experimental and theoretical, in the field. Materials discussed are AlN, GaN and InN and the ternary alloys between them.