Second look surgery (SLO) has two kinds of significance in therapy of ovarian cancer. One is a diagnostic value in persistence or not of ovarian cancer. The other is a second cytoreductive surgery. SLO as a diagnostic value is very much valuable to determine prognosis and therapies. On the other hand, SLO as a second cytoreductive surgery prolonged survival periods, however did not affect long term survival rate. Hence, their significance of SLO is not established to acquired good prognosis in long term.