RNase activities in saliva of 30 patients with breast benign tumors, 33 patients with breast malignant tumors and 25 healthy individuals were measured. This study was devoted to the measurement of RNase activity (alkaline and acid) in saliva of control, benign and malignant groups. The results indicated the presence of a highly significant elevation (p<0.001) of these enzyme's activities in cancer groups in comparison with those of other groups. Upon conventional electrophoresis of the crude saliva samples of the above three studied groups, differences in the patterns of proteins and RNase activity were recognized.