Two experiments were conducted to determine intestinal disaccharidase ac- tivity in 1-day-old commercial turkey poults inoculated with astrovirus. Small intestinal sam- ples were collected on days 0.5, 1, 3, and 7 postinoculation (PI) in Expt. 1 and on days 7, 10, and 14 PI in Expt. 2 and evaluated for specific maltase activity (SMA). Astrovirus infection was verified on day 7 PI by immune electron microscopy of intestinal contents. Inoculated poults developed diarrhea and a transient, significant decrease in intestinal SMA. SMA was significantly (P < 0.05) lower in astrovirus-inoculated poults than in control poults throughout the entire small intestine from day 3 through day 7 PI. However, SMA had returned to normal in inoculated poults by day 10 PI and was significantly higher than control values (P < 0.05) in all sections of the small intestine, except in the proximal jejunum, by day 14 PI. Decreased SMA caused by astrovirus infection resulted in disaccharide maldigestion, mal- absorption, and subsequent osmotic diarrhea. As astrovirus was cleared from the intestinal tract, SMA was restored and diarrhea was resolved.