Abstract: We have previously demonstrated that 1, 25-dihydroxyvitamin D3 decreases endotoxin-induced mortalities of rat and mouse from 80% and 70% to 14% and 10% (unpublished results). In the present study, pretreatment of 1, 25-dihydroxyvitamin D3 decreased pad oedema and pulmonary vascular permeability induced by scalding and platelet-activating factor. 1, 25-Dihydroxyvitamin D3 in a dose of 4x10–9 mol/kg decreased pulmonary extravascular Evans blue concentration increased by platelet-activating factor from 6.32 ± 0.63 ng/g to 2.57 ± 0.28 ng/g (P<0.01), and lung water/dry lung weight from 3.79±0.57 to 1.51±0.13 (P<0.01). 1, 25-Dihydroxyvitamin D3 of 4x10–11 moles/kg and calcipotriol (a vitamin D analogue which has limited hypercalcaemic effect) of 4x10–9 moles/kg had similar effects. Karyocyte counting of bronchoalveolar lavage fluid and the reduction of mean arterial pressure were also reduced to some extent. These results suggest that 1, 25-dihydroxyvitamin D3 may be a new and effective drug to reduce vascular permeability and ameliorate oedema.