The reliability of saliva as an indicator of rotavirus infection was assessed among 15 infants (3-12 months) with rotaviral and 15 with nonrotaviral diarrhea. Paired salivary samples collected during acute and convalescent phases were tested for rotavirus-specific IgA and IgM by an ELISA. The sensitivity of IgA or IgM alone to predict infection was 53.3% and 46.6%, respectively; used in conjunction, the sensitivity rose to 80%. It seems that infants with rotaviral diarrhea mount mucosal antibody responses as reflected in their saliva; possibly salivary antibodies could be used to evaluate vaccine "take" in rotavirus vaccine trials.