History and Objectives: Minor thalassemia is one of hereditary diseases, due to different prevalence of this disease in first and second degree relatives of patients with major Thalassemia and in order to determine the prevalence of minor thalassemia in these individuals this study was performed in Kashan in 1377-1378.

Materials and Methods: A descriptive study was performed on the first and second-degree relatives of 20 patients with major thalassemia. In this study first-degree relatives were considered as grandfather, grandmother, sister and brother and second-degree relatives were considered as uncles and aunts. Minor thalassemia was defined as MCV less than 80 and HbA2 more than 3.5%. In this study after obtaining permission, patients with major thalassemia were included in the study and then their first and second degree relatives were evaluated from the following points: Sex, inhabitant, educational level, familial marriage, HbA2, MCV and the presence of minor thalassemia.

Results: From the 124 persons, 24 of them (39.5%) were urban and 75 (60.5%) were rural inhabitants. Minor thalassemia was most commonly found among illiterate persons (16.9%) and less commonly observed among highly educated individuals (0.8%). This study showed that the prevalence of minor thalassemia in the population under study is 37.9% (14.5% in females and 26.5% in males). Familial marriages occurred in 54% of the affected persons (60.5% in rural and 39.5% in urban inhabitants).

Conclusion: Considering Iranian culture in which familial marriages are common, increasing numbers of patients with major thalassemia is anticipated. Therefore increasing public knowledge by mass media, radio and television can help to improve this problem. In order to decrease the prevalence of minor thalassemia in general population, education as schools in this regard recommended.