Objective　To investigate the expression and clinical significance of aPKC-ι and MUC1 in human breast cancer，and analyze molecular mechanisms of the invasion and metastasis of breast cancer. Methods　The expression of aPKC-ι and MUC1 in 106 specimens of breast cancer were detected by immunohistochemistry， and their correlations to the clinicopathologic characteristics of breast cancer were analyzed. The correlation of aPKC-ι expression to MUC1 was analyzed by Spearman′s rank correlation. Results　The expressions of aPKC-ι and MUC1 had some relation with metastasis， histological grade and clinical stages of breast cancer(P＜0.05)， but they had no correlation with age， menopause， T stages and M stages(P＞0.05). Expressions of aPKC-ι and MUC1 increased gradually with the progress of metastasis， histological grade and clinical stages(P＜0.05). The positive correlation was observed between aPKC-ι expression and MUC1 expression in breast cancer(r＝0.537，P＜0.05). Conclusions　 The expressions of aPKC-ι and MUC1 may reflect the metastasis， histological grade and clinical stages of human breast cancer. The interaction of two factors plays an important role in regulation of the invasion and metastasis of breast cancer cell， and it is possible for aPKC-ι to adjust importantly in role as a tumor metastasis inhibition protein.