In this paper, a proposed PID tuning rules for general known or unknown plant models are presented. The design procedure used to obtain the tuning rules has been previously used in literature to obtain tuning rules, but for dedicated plant models. Our contribution in this article is that the proposed tuning rules are applicable for general plant models. These rules are designed to be robust for plant gain variations. The design procedure is based on some specification or constraints of frequency response, namely phase margin, gain crossover and robustness condition. The designed rules are given in terms of frequency response parameters of the plant model ‘which can be found experimentally’ instead of the plant model transfer function (T.F.) parameters. So, these rules do not need the model of controlled process to be known. Simulation study showed clearly the generality, ease of use, good performance and robustness of the obtained tuning rules. Simulation study has included comparison study with other known tuning rules.