Objective. To investigate the relationship between Vascular endothelial growth factor (VEGF) gene expression and protein kinase C (PKC) activity. Method. 1) Rat's primary pulmonary artery endothelial cells (PAEC) were cultured under hypoxia condition (1% O2). Changes of PKC activity and VEGF mRNA in PAEC were detected at 0 (control), 1, 3, 6, and 12 h in the hypoxic condition of culture. 2) After addition of PKC inhibitor (staurosporine) in culture medium and culturing PAEC in hypoxic condition immediately, PKC activity and VEGF mRNA in PAEC were measured at the same time. VEGF protein in culture medium under the two conditions above were also detected. Result. PKC activity in PAEC were obviously elevated at 1 h during hypoxia as compared with the control (P<0.05); VEGF mRNA expression in PAEC and VEGF protein level in culture medium were increased significantly (P<0.01) at 3 h and 6 h during hypoxia respectively as compared with the control (P<0.01); After addition of PKC inhibitor in culture medium and culturing cells in hypoxia condition immediately, PKC activity in PAEC decreased significantly as compared with that at 0 h (P<0.01), and there were no significant changes of VEGF mRNA in PAEC and VEGF protein level in culture medium at any time (P>0.05). Conclusion. The results demonstrate that hypoxia stimulates pulmonary arterial vascular endothelial cells to secrete VEGF, and PKC may be one of the factors that up-regulate VEGF gene expression during hypoxia.