Mg delta-doped GaN epilayers have been grown by metalorganic chemical vapor deposition, and their characteristics have been investigated. It is shown that not only the p-type conduction, but also the overall quality of p-GaN is improved by delta-doping. It is observed that the dislocation density is reduced due to the growth interruption. A pre-purge step has been employed during delta-doping process, but the carrier concentration was decreased by the pre-purge.