An enzyme-linked immunosorbent assay was developed for the detection of specific salivary IgA antibodies toGiardia lamblia.Among 73 infants and children in a day care center 9 asymptomatic subjects had stools positive forG. lamblia.Salivary antigiardia IgA concentrations, expressed as OD units, were higher in the 2− to 4-year-old group: 0.899 ± 0.03vs.0.660 ± 0.03 in the <2-year old group (P< 0.001). In both groups values were higher in the infected children (1.099 ± 0.04vs.0.629 ± 0.09 in the < 2-year-old group and 1.053 ± 0.07vs.0.859 ± 0.03 in the 2-to 4-year-old group). In children infected throughout the study period, salivary antigiardia antibodies remained consistently high and in 2 children whose stools were initially negative a significant rise in OD value was observed after stools tested positive. Total salivary IgA did not differ between the two age groups and did not correlate with specific salivary antigiardia antibodies in individual subjects. The enzyme-linked immunosorbent assay for detection of specific salivary antibodies to G.lambliacan be used in the study of the mucosal immune response to the parasite, and may serve as an screening tool in monitoring the exposure of various populations to G.lamblia.