We evaluated subject safety and the fMRI image quality in the presence of transcranial alternating current stimulation (tACS). Scalp temperatures under the tACS electrodes with and without stimulations were measured. Result indicated: i) the tACS stimulation itself had no harmful impact on scalp temperature; ii) tACS’s artifacts had negligible effects on fMRI images. Although the fMRI scan produced heating effects due to the RF energy deposition in tACS electrodes, the scalp temperatures remained below 37°C during a 12-min scan regardless of the presence of stimulations. Thus, concurrent tACS with fMRI has no impact on patient safety and image quality.