Concurrent administration of external beam pelvic radiotherapy (RT) and chemotherapy (CT) is an effective treatment modality for rectal cancer. In adults in reproductive age, one of the most important side-effects resulting from this treatment is gonadal toxicity. Fortunately, it is possible to protect the ovaries by transporting them out of the RT area through lateral ovary transposition (LOT), as a minimally invasive method, which is performed before the application of RT. A 24-year-old female was diagnosed as having rectal adenocarcinoma in May 2003, and she was scheduled to receive adjuvant 5-fluorouracil-based CT followed by concurrent chemoradiotherapy (CRT). Before the onset of the adjuvant treatments, laparoscopic LOT was performed, and the patient was followed-up appropriately. Although amenorrhea developed during the CRT, the menstrual cycle of the patient resumed without performing any medical treatment eight weeks after the completion of the CRT. In July 2005, the patient became pregnant spontaneously with no local or systemic recurrences of rectal cancer. The present case shows that ovarian functions can be successfully protected in rectal cancer patients receiving RT by laparoscopic LOT, and by modifying the RT fields.