A case is presented of Whipple's disease with mild gastrointestinal symptoms. Abdominal ultrasonography and breath test after lactose load were of great help in the diagnostic phase and follow-up. Ultrasonography showed dilated and thickened ansae and abdominal lymph nodes which were considerably increased in volume and markedly hyperechoic; this latter aspect would seem to be typical of lymph adenomegalia secondary to Whipple's disease and is linked to the accumulation of fats. The breath test showed two H2 peaks, the first being early (30 min after lactose intake) suggesting high seated bacterial colonization. Intestinal biopsy confirmed the diagnosis of Whipple's disease. After 40 days of antibiotic treatment the clinical and laboratory pictures were almost normal and the breath test showed complete disappearance of H2 production, thus confirming the effectiveness of the treatment in eradicating the intestinal bacteria.