Good control of processes with long dead time is often achieved using a Smith predictor configuration. However, not much work has been carried out on obtaining simple tuning rules for a Smith predictor scheme. This paper develops optimal analytical tuning formulas for proportional-integral-derivative (PID) controllers in a Smith predictor configuration assuming perfect matching. Exact limit cycle analysis has been used to estimate the unknown parameters of a first-order plus dead time (FOPDT) or second-order plus dead time (SOPDT) plant transfer function. Simple analytical tuning rules based on these FOPDT and SOPDT are then derived which can be used to tune a PID controller in a Smith predictor scheme. Some examples are given to show the value of the approach presented.