Iron deposition in the respiratory system has been proposed as a potential cause of the ventilatory restrictive impairment seen in patients with thalassaemia major (TM) and iron overload. In this study, magnetic resonance imaging (MRI) measurements of the liver (T2 relaxation time) were used as a surrogate index of total body iron burden and the extent to which these measurements correlated with total lung capacity (TLC) in patients with TM was examined. Twenty-one patients (aged 25+/-5 yrs) with TM participated in the study. Standard pulmonary function tests were undertaken and the T2 relaxation time of the liver was measured in all patients. Ventilatory restrictive impairment (mean TLC 74+/-11 (SD)% predicted) was the most common abnormality found in 71% of TM patients. There was no correlation between TLC (% pred) and T2 relaxation time (r=0.06, p=0.78). T2 relaxation time correlated weakly with average serum ferritin levels (r=-0.56, p=0.008). In conclusion, the data do not support the notion that the restrictive impairment in patients with thalassaemia major and iron overload is related to iron deposition in the respiratory system.