Background: Recent studies have reported CD10 and p63 expression in myoepithelial cells (MEC) of the breast, supporting its use as a marker to help distinguish invasive breast carcinoma (IC) from ductal carcinoma in situ (DCIS). Aim: To compare the effectiveness of CD10 and p63 with smooth muscle actin (SMA) in the detection of MEC in duct carcinomas in situ and invasive duct carcinomas of breast. Methods: Histological material from 26 patients with DCIS and 35 with IC were immunostained for CD10, p63 and SMA.