Variations in manufacturing processes are expected to fluctuate around a constant level called the process mean. This article is concerned with the development of a control chart that detects cycles in the process mean. The new control chart, the spectral control chart, is based on the periodogram. The value plotted at each point in time is the ratio of the largest periodogram ordinate to the average of all ordinates. When an observation falls above the prescribed control limit, an out-of-control signal is given. The spectral control chart is compared with the Shewhart and geometric moving average charts. Data obtained from Monte Carlo simulations show that the spectral control chart is superior for detecting cyclic variations but that it is not effective for detecting shifts in the process mean. Thus the spectral control chart should be used along with existing control charts so that both shifts and cycles in the process mean can be detected.