Eight lectins were used to study 100 cases of breast carcinoma and 56 cases of non-cancerous breast tissues by lectin histochemical method. The results showed that Bandeiraea Simplicifolia (BSL) and Peanut agglutinin (PNA) had higher positive rates in breast carcinoma than both normal breast and benign breast lesions (P less than 0.005). The positive deposit in malignant lesions was mainly located in cytoplasm while in non-malignant lesions, it was almost always lined along the lumen of glands (P less than 0.005). The authors think that expression of PNA-receptor in the cytoplasm might be associated with the mechanism that the tumor could escape from immune attack. Comparative analysis on the normal breast indicated that PNA affinity histochemistry would be useful to the understanding of the metabolism of N-acetyl-D-galactosamine during the development of normal breast and histological origin of breast carcinoma.