This paper presents a unified approach, which is based on a PID approximation of the filtered Smith predictor, for tuning PID controllers for stable, integrative, and unstable dead-time processes. The proposed control tuning method is simple to analyze and use. Case studies are included to illustrate the advantages of the proposed tuning rules. Comparisons with other existing methods are also presented to show that the proposed unified method provides promising results. Furthermore, tuning rules to obtain a reasonable trade-off between robustness and performance are derived.