The medical records and pathologic specimens were reviewed from 33 patients with complete molar pregnancy at Brigham and Women's Hospital between 1980 and 1989. Two pathologists (D.R.G. and R.W.R.) reviewed all slides from the original sharp curettage to identify pathologic features that may be associated with persistent gestational trophoblastic tumor (GTT). The pathologic features evaluated were implantation site, presence of myometrium, presence of villi, presence and degree of atypia in cytotrophoblast, syncytiotrophoblast and intermediate trophoblast, presence of fibrinoid, presence of implantation site inflammatory cells, volume of tissue and area of trophoblastic tissue. Only one pathologic feature, fibrinoid deposits, identified in sharp curettings was associated with the development of persistent GTT. While 12 (48%) of 25 patients who attained remission without chemotherapy had fibrinoid deposits, only 1 (12.5%) of 8 patients who developed persistent GTT had them (P less than .10).