Forty five samples representing 15 brands of processed cheese
(3 samples each) were grouped into two categories based on the origin of fat in cheese namely; cheeses containing exclusively milk fat and that containing vegetable fats. The cheeses were analysed for their fat, total solids and ash contents. Also, cheese fat was extracted and analysed for its diene contents and thiobarbeturic acid (TBA) values. Correlations between, diene contents and TBA values and reported values were calculated. The total solids and fat content of all samples were found to meet the requirements of the Egyptian Standards for processed cheese. Processed cheeses containing only milk fat had higher diene contents than that containing vegetable fats. Wide variations were observed in the TBA of cheese from different brands. Low correlations were found between diene and the conjugated linoleic content of cheese fat.