There has been no review study published yet comparing the effects of the vasodilating drugs that are most often used in clinical practice empirically. The aim of the authors' study was to perform this comparison and to select the drugs that are able to release vasospasm and the drugs that reduce vasospasm duration most effectively in an experimental model in vivo.Pedicled groin flaps were dissected in 300 male Wistar rats. Vasospasm was induced by tension applied on the pedicle in the axial direction using a 15-g weight. The blood perfusion of the flap was monitored using a laser Doppler device. The duration of vasospasm was defined as the time from the release of tension until blood flow began to rise. These times were detected using automated computerized detection. The effects of 11 different drugs were studied in 14 groups. The drugs were applied locally; some of them were tested in different concentrations or applied parenterally.Ten percent magnesium sulfate reduced the duration of vasospasm most effectively (p < 0.01). Verapamil applied locally and also pentoxifylline applied parenterally were also very effective. In contrast, the duration of vasospasm was extended after local application of 2% lidocaine (p < 0.01).The authors concluded that 10% magnesium sulfate applied locally has the best ability to relieve surgically induced vasospasm because of the highest level of significance and reliability. The finding that local application of 2% lidocaine prolongs vasospasm may be surprising.