Background: The prevalence of short stature was reported high in thalassemia major patients. It causes mental and social problems for them. As different cut-off points for growth retardation are suggested in these patients, it is desirable to find a careful cut-off age using statistical analysis to help patients before it is too late. Methods: Data from 803 thalassemia major patients was extracted from questionnaires completed in person by the operator. They contained demographic data, family, medical, and drug history. Height and weight measurements were conducted by only one device. The mean age was 20±7 years and there were 420 females in the sample. Children (