Apoptosis regulation has been implicated as a main cause of epithelial dysfunction in patients with ulcerative colitis. Apoptosis can be divided into distinct pathways, which depend on the expression of a large number of apoptosis-related genes. The aim was to elucidate which pathways are dominant in normal and inflamed colonic epithelial cells. An apoptosis-specific gene array expression profiling system of 96 genes was used to determine the expression profile of apoptosis-related genes. Epithelial cells isolated from three patients with active ulcerative colitis were pooled and compared to pooled epithelial cells isolated from three control subjects. Genes found to be three-fold or more overexpressed in ulcerative colitis were subsequently analysed by PCR in a larger population (10 patients with ulcerative colitis, 8 control subjects). Selected genes found not to be regulated were additionally tested by PCR in the same population. Six genes were found to be highly expressed in epithelial cells from both controls and ulcerative colitis patients. These included Bcl-2 antagonist/killer, B lymphoid tyrosine kinase, caspase 14, Harakiri, tumour necrosis factor (TNF) receptor 2, and TNF receptor-associated factor 1 (TRAF1). Three genes were found to be upregulated in ulcerative colitis (p