 Train of four TOF test is method used to determine level of neuromuscular blockade, by stimulation of peripheral nerve and following induced muscle contractions. Interpretation of muscle contractions may be by subjective visual or objective quantitative method. Quantitative TOF test may be used prior screw stimulation test by calculating T4T1 ratio and obtaining quantitative value which shows level of neuromuscular blockade. Residual neuromuscular blockade may be present before screw stimulation test, and effect on accuracy of this test in this situation was not clearly investigated in recent studies. 