Background: A Disintegrin and Metalloprotease Domain 29 (ADAM29) is involved in many important physiological processes. Recent studies have demonstrated that ADAM29 is a susceptibility locus showing traits as a risk factor for breast cancer under genome-wide significance, however, the clinical relevance and cellular function of ADAM29 in breast cancer have not been reported. Materials and Methods: In this study, we assessed the expression levels of ADAM29 in a cohort of human breast cancer specimens. We also used MDA-MB-231 cells with differing ADAM29 expression and assessed the influence of ADAM29 and its mutations on the MDA-MB-231 cell line. Results: Increased transcript expression of ADAM29 was observed in breast cancer tissues compared to normal ones. The expression of ADAM29 and its mutations in different domains significantly influenced proliferation, migration and invasion of breast cancer cells in vitro. Conclusion: ADAM29 may represent a prognostic factor in human breast cancer, as well as a novel molecular candidate to be used as a therapeutic target.