Mixed lobular and ductal carcinoma in situ is very rare. We recently experienced a case of invasive lobular carcinoma associated with mixed lobular and ductal carcinoma in situ in a 50-year-old female. The infiltrating portions of lobular carcinoma revealed thread-like strands of tumor cells. Lobular carcinoma in situ with pagetoid spread into the ducts and ductal carcinoma in situ of the predominantly papillary type were also noted in the same mass.