Abstract Literature dating back to the early 1960’s has shown that AC current can cause corrosion of cathodically protected steel under laboratory conditions. Until recently however, there has been little evidence to suggest that AC corrosion of cathodically protected structures may be of practical concern. In Ontario over the past six years, the authors have investigated several corrosion anomalies occurring on pipelines exposed to induced AC interference. This paper discusses a number of such cases where AC corrosion was suspected The test procedures used to identify AC corrosion are discussed, as are some of the methods for minimizing the risk of AC corrosion.