Gating of myocardial perfusion imaging helps to differentiate artifacts from perfusion defects. We used this technique to evaluate the impact of routine gating on the interpretation of results by physicians experienced in this field. We studied, prospectively, 270 consecutive patients (161 men and 109 women) who underwent gated myocardial perfusion imaging. Single-photon emission-computed tomography was performed to evaluate myocardial perfusion in patients at rest and after stress, using technetium-99m sestamibi and post-stress gating. Participating physicians interpreted each study and indicated a confidence level for the interpretation. Initially, these opinions were formed on the basis of static slices alone and subsequently, with the addition of gating information. The impact of gating was evaluated by the number of studies in which gating led to a change in interpretation from normal to abnormal or vice versa, or from borderline to definite. The interpretation was changed from abnormal to normal or vice versa in 10 studies (3.7%) and from borderline to definite in 3 (1.1%). In 37 studies (13. 7%), the confidence level was increased from confident to very confident with no change in interpretation. We conclude that routine gating of every myocardial perfusion imaging study for the identification of artifacts is of low value for physicians experienced in interpreting such studies. Although gating frequently increases the confidence level, it seldom leads to a change in interpretation. Specific subgroups of patients who would benefit from gating should be identified.