Background and Objectives: Complete hydatidiform MOLE is the most common form of trophoblastic disease, the incidence of which greatly differs geographically and is fairly high in our country too. The aim of this study was to determine the frequency of molar pregnancy in our patients and assess the ultrasonic findings of the disease.Materials and Methods: From July 1985 to February 1997, 11,370 women with normal or pathologic pregnancies underwent ultrasonic examination in Obstetrics and Gynecologic (Al-Zahra) Hospital of Faculty of Medicine, Tabriz University of Medical Sciences and Azarbaijan Radiologic and Sonologic Clinics (Private). Results: Among 11,370 patients, 10,414 women had normal pregnancies and from 935 remainders with different associated pathologic conditions, 100 patients had hydatidiform MOLE (98 complete and 2 partial MOLE). In this study, the incidence of hydatidiform MOLE was 8.7 in 1000 pregnancies which approximate to Saleh and co-worker's study (1964-65), but has considerable differences in comparison to Javey and Sajjady’s findings (1970-75) and the Western and the Far East countries statistics.Conclusion: Occurrence of hydatiform MOLE is not a common finding, however its prevalence is fairly high in our country in comparison to other studies reported earlier.