Ultraviolet (UV) light is the most important environmental insult to skin. Even a single exposure to UVB radiation can result in inflammation and may also lead to DNA damage and apoptosis in the acute response of the cutaneous tissue. To elucidate the complex alterations of gene expression in human keratinocytes underlying these UV responses we took advantage of differential display polymerase chain reaction (DD-PCR) technology's ability to detect qualitative and quantitative changes in gene expression in more than two cell populations simultaneously. We demonstrate that low-dose UVB (100 Jm-2) leads to both induction and downregulation of different genes during the 24 h after irradiation in a time-dependent manner. In addition to the identification of known genes as possible effectors or targets in the UV response of human keratinocytes, we here identify a new sequence that is negatively regulated by UVB irradiation and was termed HUR 7 (HaCaT UV repressed). In general our results showed that DD-PCR is a useful tool in the analysis of quantitative changes of mRNA levels in human keratinocytes after UV irradiation. The identification of new UVB-repressed genes offers the opportunity to identify unrecognized molecular mechanisms in the UV response of human cells.