Patients with thalassemia intermedia (TI) experience many complications, of which the incidence varies greatly among cases. Considering the high prevalence of thalassemia in Iran, the study was carried out to determine the frequency of TI complications in Iranian patients and to find possible risk factors for each of them. Using the sampling method of "census," the authors included 153 patients who were seen in their tertiary hematology clinic with the diagnosis of TI during 1996-2010; an analytical cross-sectional study was performed and the data was analyzed by SPSS software using univariate and regression analyses. Mean age of the patients at the time of the study was 17.4 years and 36.5% were receiving transfusions (regularly or occasionally). Mean hemoglobin was 9.2 g/dL and mean serum ferritin was 858 ng/mL. Splenectomy was performed in 46.9% and it was correlated with age and the age at diagnosis in regression analysis. Cholelithiasis was found in 25.5% and was correlated with age and history of splenectomy. Pulmonary hypertension, detected in 23.5%, was correlated with thrombocytosis and mitral valve regurgitation in univariate analysis. Endocrine disease (hypogonadism, hypothyroidism, and adrenal insufficiency) was detected in 8% of the patients. In univariate analysis, endocrine disease was correlated with age of the patients. Regarding bone density of the spine, 53% of cases had osteoporosis. Thrombocytosis was present in 42% of patients and was correlated with their age. Since the severity of thalassemia intermedia vary greatly among patients, a careful evaluation of clinical, laboratory, and genetic aspects is necessary to differentiate TI in a patient at presentation. Moreover, TI patients should be carefully followed up for early detection and management of newly developed complications. The authors also suggest confirmatory controlled studies with larger sample sizes to assist in developing guidelines for surveillance and treatment of TI.