A case of Henoch-Schönlein purpura (HSP) characterized by several unusual complications and exceedingly prolonged course is reported. A 6-year-old boy, hospitalized with a typical clinical picture of HSP, developed after a few days a severe gastrointestinal vasculitis leading to digestive hemorrhages and food intolerance. The treatment included continuous gastrointestinal infusion, parenteral nutrition, and corticosteroids during the exacerbations of symptoms. Intestinal ultrasonography showed diffuse submucous edema and widespread mural hematomas; hydrops of the gallbladder and edematous swelling of the pancreas were also detected. A gastro-duodenoscopy revealed diffuse and severe mucosal vasculitis with ulcers and petechial lesions. One week after admission the occurrence of weight gain, hyponatremia, and hypoprotidemia in the absence of proteinuria suggested a protein-losing enteropathy. The elevation of serum and urine amylases was consistent with pancreatic involvement. The course was characterized by recurrent exacerbations of gastrointestinal manifestations; symptoms subsided slowly to such a degree that oral feeding could be gradually restarted only seven weeks after admission. The use of high-frequency intestinal ultrasonography proved useful and sensitive in monitoring the evolution of intestinal involvement. During hospitalization the child complained of acute painful scrotal swelling. Ultrasonography showed scrotal hemorrhage and testicular swelling but no signs of testicular torsion, thus helping to avoid surgical exploration. In the recovery phase the child complained of colicky abdominal pain with vomiting. A plain abdominal roentgenogram showed bilateral staghorn pelvic urolithiasis. This finding was confirmed by an intravenous pyelography which also revealed a bilateral pyeloureteritis with edema of the ureteral wall and partial stenosis of the lumen.(ABSTRACT TRUNCATED AT 250 WORDS)