Prevention programs are considered to be a top priority in Iran because beta-thalassemia (beta-thal) major (TM) is the most common autosomal disorder in Iran, and in the Mazandaran Province in particular. The main strategies comprise providing appropriate information for the public and professionals, screening and counseling of families at-risk and screening of general population prior to marriage. Providing laboratories for prenatal diagnosis was the most recent step in the program. We report the results of our prevention campaign for the period 1993-2006 in order to assess the effectiveness of all actions in controlling thalassemia major. In 1993, 500 TM patients were registered at the clinic of the Boo Ali Sina Hospital, Sari, Mazandaran, Iran. From 1993 to 1996, on average of 50 new cases were added to the cohort annually, whereas from 1995 to 2005 the number of new cases declined to 35 per year. Furthermore, the patients' average age increased. Overall, 51% of couples at-risk, who received genetic counseling, decided not to marry. All at-risk couples who are married were counseled for prevention of unplanned pregnancies. Currently, 64% are using safe contraceptive methods of family planning, and 14% are no longer at-risk for further pregnancies, the rest remained at-risk for unplanned pregnancies. In conclusion, at the relatively low cost of premarital screening and genetic counseling, we have offered at-risk couples the possibility of preventing the birth of at least 600 undesired TM patients. Thus, a great deal of suffering and an unbearable financial burden has been prevented to patients and their families.