Abstract: Objective To study the therapeutic effect of lapatinib on HER-2 positive advanced breast cancer and its toxic and side effect. Methods Clinical data about 23 patients with HER-2 positive advanced breast cancer who received lapatinib treatment in our hospital from December 2007 to December 2011 were analyzed. Time of disease progress, effective therapeutic rate, beneficial clinical rate, and toxic and side effect were observed. Results The total effective rate and beneficial clinical rate of lapatinib was 65.2% and 86.9%, respectively, for HER-2 positive advanced breast cancer. The time from median to disease progress was 11.9 months. The main toxic reactions to lapatinib were diarrhea, hand-foot syndrome and oral mucositis. No grades 3-4 toxics reactions occurred. Conclusion Lapatinib is an effective and well-tolerated molecular targeting drug for HER-2 positive advanced breast cancer.