We reviewed our clinical experience of olaparib treatment for patients with platinum-sensitive recurrent ovarian, fallopian tube, and peritoneal cancer. Of the 10 cases, the primary sites of cancer were the ovaries, fallopian tubes, and peritoneum in 7, 1 and 2 cases, respectively. The median period of treatment administration was 10 months. The observed Grade 3 or 4 adverse events as per the Common Terminology Criteria for Adverse Events version 4.0 were: anemia, leukopenia and neut r openia in 4, 4 and 3 cases, respectively. Eight cases needed treatment to be interrupted, and 5 cases required a reduction in dose. Three patients were treated for more than 12 months, while the others had to discontinue due to disease progression. However, none of the patients had to discontinue treatment due to adverse events. Therefore, it appears that olaparib can be safely used despite some patients requiring a withdrawal or reduction in treatment.