Myoepithelial cells play an important role in the interpretation of breast fine-needle aspiration biopsy, since these cells are believed to be a component of a benign process in breast lesions. Myoepithelial cells are usually easy to recognize, however, other cells can morphologically simulate myoepithelial cells and make the distinction difficult. To assess the feasibility of immunostaining as an adjunct to identify myoepithelial cells, we have used immunocytochemistry using monoclonal antibody against muscle specific actin (MSA) in our breast fine-needle aspirates. Herein, we report our experience in immunocytochemical detection of myoepithelial cells using labeled Streptavidin Biotin Detection System on destained Papanicolaou stained smears and cell block preparations obtained from breast aspirates.