This was an exploratory study comparing neuropsychological manifestations of Sydenham's chorea (SC), 6 months after initiation of treatment, in children who had received intravenous immunoglobulins as an adjunct to standard treatment, with those who had received standard treatment. We included a non-SC control group for comparison. We hypothesized that compared to controls, children with SC who had received prior intravenous immunoglobulins would demonstrate less pronounced impairments compared to those who had received standard care. We conducted a cross-sectional analysis of 17 children with -SC who had received treatment 6 months previously (9 treated with standard of care and 8 augmented with intravenous immunoglobulins) and 17 non-SC, medically well controls. The standard treatment group (n = 9) exhibited significant behavioral difficulties, including significantly poorer co-operation (p = 0.009) compared with the other augmented immunoglobulins and non-SC control groups, and increased impulsivity (p = 0.016) compared with non-SC controls. The standard treatment group scored significantly lower than the other two groups on a measure of executive functioning (p = 0.03). Children with SC may be more at risk for neuropsychological difficulties than non-SC, medically well children. Intravenous immunoglobulins may mitigate some of these impairments.