Studies were undertaken to determine if human torovirus is associated with gastroenteritis and to examine the clinical features of torovirus illness in children. The fecal excretion of torovirus in patients with gastroenteritis was compared with that in matched asymptomatic controls in a case-control study. Toroviruses were identified in 72 (35.0%) of 206 gastroenteritis cases compared with 30 (14.5%) of 206 controls (P < .001). Clinical features of torovirus gastroenteritis in 172 patients positive for torovirus were compared with those of 115 patients infected with rotavirus or astrovirus. Persons infected with torovirus were more frequently immunocompromised (43.0% vs. 15.7%) and nosocomially infected (57.6% vs. 31.3%). They also experienced less vomiting (46.4% vs. 66.7%) but had more bloody diarrhea (11.2% vs. 1.8%). An antibody response to torovirus developed mainly in older, nonimmunocompromised children (P < .01). These studies demonstrate an association between torovirus excretion and gastroenteritis in the pediatric population among immunocompromised hospitalized patients and in previously healthy patients.