Abstract: Objective: To explore the expression of Laminin Receptor (LN-R) and Cathepsin D (Cath-D) in malignant fibrous histiocytoma (MFH) and to investigate their relationship and clinical significance. Methods: Sixty-five samples of MFH from postoperative patients seen in Harbin Medical University Tumor Hospital between April 1999 and December 2001 were collected for this study. There were 40 males and 25 females, from 23 to 78 (mean age 54) years of age. The 65 cases of MFH were examined for LN-R and Cath-D expression by immunohistochemistry. The correlation between the protein expression rates and the clinical and pathological characteristics was analyzed. The correlation between the expression of LN-R and Cath-D was analyzed as well. Results: Positive expression of LNR was localized mainly in the cytolemma and cytoplasm, while Cath-D was localized mainly in the cytoplasm. Positive rates of LN-R and Cath-D immunostaining in MFH were 66.2% and 75.4%, respectively. In stage I~II, the LN-R and Cath-D expression rate was remarkably lower than that seen in stage Ⅲ~Ⅳ (P<0.05). The LN-R and Cath-D expression rate in well-differentiated tissues was markedly lower than that found in moderately differentiated and poorly differentiated tissues, indicating that the positive rate gradually increased with the degree of tumor differentiation. The two proteins were not detected in 10 normal fibrous tissues. The expression of the proteins was not significantly correlated with gender, age and histological type. All of the patients were followed up from 0.5 to 7 years (average 5 years). The LN-R and Cath-D positive rates were higher in patients with a life span shorter than 5 years compared to those patients with a life span longer than 5 years (P<0.005). There was a significant positive correlation between LN -R and Cath -D expression (P <0.01). Conclusion: The results demonstrate that LN-R and Cath-D may play an important role in the development and progression of MFH. LN-R and Cath-D can be employed as important markers of invasion, degree of malignancy, metastasis and prognosis.