The authors here report a case of an infertile woman with diffuse leiomyomatosis of the uterus, which is a rare benign pathological condition in which the myometrium is occupied by innumerable small fibroid nodules. Due to the progressive abdominal distension of the patient and the desire for pregnancy of the couple, myomectomy was performed as a primary treatment. Urgent relaparotomy was required for hematoma debridement on the following day. Despite the evidence of the follicular growth and cyclic ovarian steroid secretion, the patient had postoperative endometrial thinning that was unresponsive to hormone replacement therapy. Supplementation of oral tocopherol nicotinate/vitamin E and ascorbic acid/vitamin C was effective for immediate recovery of withdrawal bleeding and gradual gain of endometrial thickness. The patient had a successful pregnancy in an in vitro fertilization-embryo transfer program and gave a birth to a healthy baby.