The incidence of early anaphylactic reactions to scorpion antivenom given i.v. after Tityus serrulatus scorpion sting was evaluated in 103 children aged up to 15 years in Belo Horizonte, Brazil. Patients without adrenergic manifestations (Group 1, n = 28) were compared with those who presented systemic involvement that included adrenergic manifestations (Group 2, n = 75). Data were recorded on a proforma and the presence or absence of early anaphylactic reaction was cross-tabulated according to clinical features, sex, age and volume of antivenom used in the treatment. Unpaired Student's t-test was used to calculate significance of differences in age and volume of antivenom used. Multivariate logistic regression was used to determine the effects of clinical features and volume of antivenom as predictors of early anaphylactic reaction to antivenom treatment. Twelve (42.9%) of 28 children included in Group 1 presented early anaphylactic reactions compared with 6 (8%) of 75 children of Group 2 (OR = 8.63; 95% CI: 2.88, 25.7). The reactions were more severe in Group 1. There were no significant differences with respect to age and sex. After adjusting for clinical form, volume of antivenom was not significantly associated with presence of reactions (OR = 1.11; 95% CI: 0.70, 2.80 for each 5.0 ml of antivenom administered). The results show that children with adrenergic manifestations after T. serrulatus scorpion sting had significantly lower anaphylactic reactions to antivenom than those without these manifestations.