We studied the mRNA expression of surfactant proteins (SP) A, -B, -C and -D and Clara cell secretory protein (CC10) with RT-PCR and in situ hybridization and protein expression of CC10, SP-A and -D with immunohistochemistry in the lungs of a preterm rat model, in which experimental BPD was induced by prolonged oxidative stress. The gene discussed is SCGB1A1; the disease is bronchopulmonary dysplasia.