Background: Considering the importance of hydatidiform mole and its higher prevalence in Asian countries including Iran and also with respect to the lack of informative data the present study was conducted to determine the frequency of hydatidiform mole in samples referred to the pathology laboratories in Kashan during a seven-year period, 1992-99.

Materials and Methods: It was a descriptive study. For this, all patients hospitalized in Shaheed Beheshti and Shabihkhani hospitals with confirmed diagnosis of hydatidiform mole were identified through the medical records.

Results: During the study period, 85 cases of hydatidiform moles including 67 cases of complete and 18 cases of incomplete mole were found. The most commonly affected age group was ?20 years (53.3%). Meanwhile, those greater than 45 years old have shown another increment in prevalence (10.4%). 40.7% of the patients were afflicted during their first pregnancy. There was a decline in the rate of mole associated with repeated pregnancy, however, again another increase was observed in pregnancies 6 and 7. Previous history of at least one abortion was reported in 8.6% of the patients. In one patient previous history of molar pregnancy was noted. 79% of patients reside in rural region and 89% were born in Iran. Vaginal bleeding was reported to be the first presenting sign in 82.8% of the patients. 39.5% had blood type of O. Sonography has detected molar pregnancy in 78.4% of the patients.

Conclusion: Considering the higher prevalence in individuals less than 20 or those greater than 45 years old, we suggest further care for these age groups. Meanwhile, patients with vaginal bleeding should follow up thoroughly.