Among the different methods for pasteurization of foodstuff, non thermal methods include electromagnetic method has received more attention, Because of significant reducing in total count of Bacteria, preventing from spoilage and increasing shelf life of foodstuffs. In this study yolk liquid was pasteurized by using electromagnetic method in 3 different frequencies (2950-3950-4500 MHz) for constant time of 12 sec (6 sec of second pulse) and then results were compared with samples which were pasteurized at 65 C for 120 sec and control samples, after different times of storage(1,3,5,8,10 and 15 days). Results showed that used electromagnetic waves had significant effect on reduction of logarithmic count of aerobic mesophilic bacteria. According to results, however thermal pasteurization had a greater bactericide effect at zero time than cold pasteurization, but, a great increase was occurred in the number of aerobic mesophilic bacteria after passing time, in comparison with non thermal pasteurized product. According to Iranian National Standard, in electromagnetic method liquid yolk shelf life has been defined 14 days which it is very ideal in comparison with thermal pasteurization (7d max) and control sample (2d max)

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