New definitions of functional disorders in general and nonulcer dyspepsia in particular were published in the period of review. Although the definition of functional dyspepsia as persistent or recurrent unexplained upper abdominal pain or discomfort stayed essentially the same, new definitions of dyspepsia subgroups were introduced based on the predominant symptom; a reflux-like dyspepsia subgroup was not supported. It is hoped that these criteria, derived by a consensus among international experts in the field, will improve the reliability and the interpretability of future epidemiologic and interventional studies. A wide range of studies dealt with the role of putative etiological factors in functional bowel disorders including Helicobacter pylori, altered visceral sensation, or upper intestinal motility. Although eradication of H. pylori does not seem to relieve dyspepsia over placebo in recent studies of nonulcer dyspepsia, eradication of H. pylori has generally been advised because of suspected beneficial long-term effects (eg, treatment of misdiagnosed ulcer disease) that probably overweigh the potential risks.