Thalassemia is common in Iranian population. This case-control study was performed on patients with β-thalassemia minor to determine the maternal and fetal outcomes and describe most risk factors associated with β-thalassemia minor during pregnancy. This study consisting 517 β-thalassemia minor subjects is one of the biggest studies of its kind in Iran. Perinatal mortality (p=0.38) and Apgar score at 1min (p=0.65) and 5 min (p=0.25) after delivery were similar in patients with and without minor β-thalassemia minor. This is consistent with previous studies (9-13).