The constitutive expression of nuclear-factor-kappaB (NF-kappaB) in human pigment epithelial (hRPE) cells cultivated in vitro and the possible changes when incubated with PDTC and IL-1beta were investigated. The synchronized hRPE cells in vitro were divided into two groups. In non-PDTC group, hRPE cells were exposed respectively to IL-1beta and NS (for detecting the constitutive expressions of NF-kappaB in hRPE cells); In PDTC group, PDTC-pretreated hRPE cells were exposed respectively to IL-1beta and NS (for detecting the constitutive expression of NF-kappaB in PDTC-pretreated hRPE cells). The expression of NF-kappaB in hRPE cells in two groups was detected by immunofluorescence stain and flow cytometry. The results showed that the constitutive expression of NF-kappaB in hRPE cells in vitro was 8.05%, and increased to 30.26% by IL-1beta. After PDTC pretreatment, the constitutive expression of NF-kappaB in hRPE cells was decreased to 3.74%, and 3.66% by IL-1beta respectively. It was concluded that the expressions of NF-kappaB in hRPE cells could be increased significantly by IL-1beta and depressed effectively by PDTC. Also, PDTC could significantly inhibit the activation of NF-kappaB induced by IL-1beta.