The aim of this study was to study sugar maldigestion/malabsorption in patients with functional dyspepsia using H2 breath testing. End-expiratory breath H2 after separate challenges with lactose (25 g), fructose (25 g), and sorbitol (5 g) were used to determine malabsorption, as well as small bowel transit time (SBTT). Five hundred twenty patients with functional dyspepsia received all three challenges. Smaller groups were also tested after lactulose (10 g, N = 36) and glucose (50 g, N = 90) challenges. Fructose and sorbitol were closely linked with respect to absorption and malabsorption status. Only in the case of lactose maldigestion/malabsorption was there a greater than random prevalence of malabsorption (P < 0.001) for fructose and sorbitol. In contrast to lactose, ethnic origin did not influence fructose or sorbitol malabsorption, and females predominated among fructose and sorbitol malabsorbers. In Jews, the prevalence of lactose maldigestion/malabsorption decreased in the age group of 25-55 and subsequently rose after 55, while fructose and sorbitol malabsorption decreased progressively with advancing age. With respect to small bowel transit time (SBTT), in the case of sorbitol and lactulose, it was significantly greater (P < 0.05) than those for fructose and lactose. Multiple sugar malabsorptions are common when lactose maldigestion/malabsorption is present.