Due to the use of a great number of existing chemicals and many new being produced, there is a strong need for efficient and cost-effective methods, in order to classify and regulate the use and release of these potential environmental pollutants. Effects on the environment and on human health have been described for many important toxicants; there is however a great lack of studies addressing the effects of co-exposures from such harmful agents. Toxicogenomics is a scientific field under continuous improvement and represents a hallmark of future toxicological research. Toxicogenomics has a great potential in relation to classification and risk assessments of environmental contaminants. The aim of this study was to elucidate the complex nature of co-exposures to toxicants by combining traditional toxicological tests with modern microarray technology. We investigated the effects of two well documented toxic agents; the heavy metal cadmium, and UVC irradiation (< 280 nm). Cadmium elicits many genotoxic effects, including inhibition of Nucleotide Excision Repair (NER). UVC induces DNA-lesions, mainly cis-syn cyclobutane pyrimidine dimers (CPDs) which are repaired by NER. NER plays a key role in the removal of DNA-damage caused by various toxicants. Different modes of action of cadmium and UVC make them good models for our investigations. Human testicular cancer cells (833K) were exposed to cadmium (CdCl2•2,5H2O) and UVC radiation; relevant doses were determined by measuring cell viability, and cell-cycle responses to treatments were estimated by flow cytometric analysis. DNA-repair efficiency of cells pre-incubated with 5 µM Cd2+ and exposed to UVC (1 J/m2), was assessed by measuring DNA single strand breaks (SSBs) using the alkaline elution assay. Global gene expression profiles were estimated from microarrays, whereas induction of specific proteins was measured by Western analysis. We found that cadmium treatment led to significant attenuation of DNA-repair of UVC induced lesions. Microarray analysis demonstrated differences in gene-expression profiles in response to both cadmium and UVC treatments, whereas Western analysis displayed differences in induction of specific proteins involved in DNA repair, cell cycle and apoptosis. In accordance with other studies we have found cadmium to elicit important co-genotoxic effects, especially affecting the removal of DNA damage performed by NER. We conclude that microarrays and traditional experimental toxicology, as used in the present investigations, represent adequate means to study the combined effects of toxicants.