Hyperpolarised gas ventilation MRI is a sensitive method for evaluating disease progression in subjects with cystic fibrosis and normal spirometry. Ventilation defect % (VD%) increased in 10/11 subjects studied with a mean change of 201%. The MRI coefficience of variance (CV) of signal intensity was similarly sensitive to change. 10/11 subjects had increased lung clearance index (LCI) at 2-years but no subject had abnormal spirometry at either visit. The % change in LCI demonstrated strong correlations with the % change in CV outcomes. VD% and CV reflect different but complimentary aspects of lung disease that appear to track disease progression.