To determine the seroprevalence and incidence of toxoplasmosis, 194 random serum samples of school students aged 10 to 18 yr (n = 178), their teachers (n = 10) and food handlers (n = 6) from a residential tribal school situated in district Dhule, Maharashtra state of western India, were tested. The samples were tested for anti-toxoplasma IgG and IgM antibodies using enzyme linked immuno sorbent assay (ELISA). Active infection was confirmed by a stage-specific direct agglutination test (DAT) using acetone fixed tachyzoites of T. gondii. A serosurveillance for rubella immunity was also simultaneously carried out. The results showed that at the age of 10 yr, all the children were immune to rubella infection and toxoplasma seroprevalence was detected in 20 per cent of the children. Toxoplasma infection was prevalent in 42.8 per cent adolescents, at the age of 18 yr. The average seroprevalence rate of toxoplasma infection was not significantly different in male and female children. The incidence rate of toxoplasma infection was inversely related to increase in age. The school staff comprising teachers and food handlers (aged 27 to 45 yr) showed a toxoplasma seroprevalence rate of 75 per cent (P < 0.001). There was also a significant difference (P < 0.05) in the prevalence of toxoplasmosis in children with grade II goitre (46.1%) and grade I or no goitre (31.8 and 26.5% respectively). The possible association between iodine deficiency and toxoplasma infection is being reported for the first time in this preliminary study.