Yayik butter produced by churning of yoghurt is one of the popular traditional dairy products of Turkey. In this study, yayik butter was divided into four lots. Two lots were stored with a daylight lamp at 4 and 20A degrees C (L4; L20) and the other two lots were stored at 4 and 20A degrees C in dark (D4: control; D20) for 60 days. Then, the oxidative stability of yayik butter was evaluated. The end of self life was determined from sensory data. Generally acceptability was negatively correlated with peroxide value (PV), free fatty acid (FFA), thiobarbituric acid (TBA) and titratable acidity (TA). While general acceptability of control samples (D4) was between 8.26 +/- A 0.20 and 7.80 +/- A 0.10, those of L20 sample was lower than 3.00 (dislike moderately) on 60th day. As a result of decrease detected for sensory quality, the storage process was ended. L20 sample was evaluated as unacceptable on the 60th day and the evaluation result of this sample was accepted as the limiting value. The limiting values of TA, FFA and PV, TBA were determined as 0.14 +/- A 0.01%, 1.93 +/- A 0.11 mg KOH/g oil, 0.80 +/- A 0.007 meq O(2)/g oil and 0.37 +/- A 0.02 mg malonaldehyde/kg butter in this yayik butter.