The use of DNA microarray technology in biomedical research has dramatically increased during the past years. In the present report, we provide an overview on the basic DNA microarray technology and biostatistical methods for gene expression analysis. A focus is then put on its applications in dermatological research. In recent years, a series of gene expression studies have been performed for various dermatological diseases, such as malignant melanoma, psoriasis and lupus erythematosus. These analyses have identified interesting target genes as well as putative disease susceptibility loci. However, further functional studies will be needed for a more complete understanding of the pathogenesis of these diseases. This may be performed by means of the recently developed RNA interference technology. Besides its role in large-scale gene expression studies, DNA microarray technology has proved to be a valuable tool for genomic screens of genetic alterations, e.g. single nucleotide polymorphisms. These play a role in tumour development and progression, and also function as genetic markers for disease susceptibility. Taken together, DNA microarray technology opens enormous perspectives for dermatologists. It may help us understand the complex pathogenesis of a wide variety of dermatologic diseases and identify their genetic background.