Background: Bone complications are common in patients with thalassemia. Objectives: To assess risk factors for osteoporosis in patients with nonmajor thalassemia and its prevalence in randomly selected adult patients in Thailand. Patients and methods:We included 190 adult patients (58 men and 132 women) with thalassemia intermedia or minor in this cross-sectional study. Patients with untreated hypogonadism, untreated hypothyroidism, menopause, and with a history of treatment with medications that have effects on skeletal or bone metabolism were excluded. Bone mass density (BMD) of the femoral neck was measured by calibrated dual-energy X-ray absorptiometry. Independent factors likely to be associated with osteoporosis were determined and included in the analysis to ascertain possible associations. Results: Mean age was 35.48 ± 14.11 years (range 18−87 years). The mean Z score of femoral neck was -0.86 ± 1.14 (range -3.7−2.40). Prevalence of osteoporosis was 22/190 (11.6%). Correlation between the pretransfusion hemoglobin level and BMD score was r = 0.192, P = 0.008. Univariate analysis found low BMI was a risk factor for osteoporosis (OR = 3.09, 95% CI 1.09−8.76, P = 0.039) and iron chelation therapy was a protective factor (OR = 0.24, 95% CI 0.09−0.69, P = 0.005). Multivariate analysis did not find these factors to be significant. Conclusions: All patients with thalassemia at risk of osteoporosis should be screened periodically for bone disease. The uncertainty and disagreements as to the potential role of different factors indicate the necessity for further studies to recognize the pathophysiological basis of this serious complication of thalassemia.