This report describes the clinicopathologic features of a 49-year-old woman who was reoperated on for bulky abdominal metastases 20 years after hysterectomy for endometrial stromal myosis (ESM). The levels of estrogen (ER) and progesterone (PR) receptors measured in the resected tumorous tissue amounted to 48.3 and 71.4 femtomoles (fmol)/mg cytosol protein, respectively. After medroxyprogesterone acetate (Depo-Provera; Upjohn) treatment of 16 months duration, the unresected pelvic tumor mass compressing the bladder and the left ureter had decreased in volume and hydroureteronephrosis had regressed. The efficacy of the therapy was monitored by computed tomography. Two years and nine months after surgery, the evolution of the tumor seems well-controlled by continuous progestin therapy and the patient is living without symptoms.