Abstract: Soy bean oil and sunflower seed oil were heated during frying continuously at 240℃ and 180℃ respectively and samples were taken at certain intervals for examination of polar compounds.The results indicated that the centent of polar compounds increased regularly with iacrease in the duration of frying.It is coasidered that the standard is both sensitive and regular and is a good indicator for evaluation of the sanitary quality of fryln oils.