Hypoxaemia occurring in patients with chronic renal failure (CRF) during haemodialysis (HD) has long been known. Several mechanisms of pathogenesis have been proposed. Before and after regular HD, lung ventilation (LV) and alveolar permeability (AP) were measured in 24 male patients with CRF (age, 61–75 years). LV and AP were determined by 99mTc‐diethylenetriaminepentaacetic acid (99mTc‐DTPA) radioaerosol inhalation lung scan (99mTc‐DTPA lung scan). The LV images were visually interpreted according to established criteria, including the presence or absence of an inhomogeneous distribution, inverted base to apex gradient and segmental hypoventilation. The degree of AP in the total right lung was presented as the clearance rate (K; %′min‐1) of the time‐activity curve from dynamic total right lung images. Ten male normal controls (age, 62–76 years) were enrolled in the study for comparison. Ten of 24 (42%) cases showed an inhomogeneous distribution and eight of 24 (33%) cases showed hypoventilation on equilibrium LV images. After regular HD for 5 h, no significant changes in the LV images were found. Before HD, the CRF patient group (K=1.14 ± 0.36%′min‐1) had a significantly faster clearance rate than that of normal controls (0.75±0.14%·min‐1, P<0.05). Moreover, the clearance rate after HD was significantly slower (0.87±0.15%·min‐1, P<0.05) than that before HD. CRF can predispose patients to LV change and AP damage. After HD, the damage to AP is significantly improved. However, after HD, the change in LV is not significant.