Background: Disturbances of motor circuitry are commonly encountered in Tourette syndrome (TS). The aim of this study was to investigate simple motor performance differences between boys with TS and healthy controls. Methods: We attempted to provide insight into motor network alterations by studying a group of treatment-naive patients suffering from "pure" TS, i.e., without comorbid symptomatology at an early stage of disease. We used functional MRI to compare activation patterns during right (preferred) and left (nonpreferred) index finger tapping between 22 TS boys (12.6 plus/minus 1.7 years) and 22 age-matched healthy control boys. Results: Boys with TS revealed altered motor network recruitment for right (dominant) and left (nondominant) index finger tapping. Brain activation patterns in response to index finger tapping of the nonpreferred left hand reflected the most prominent differences, including activation decrease in contralateral sensorimotor cortex while recruiting premotor and prefrontal regions along with the left inferior parietal lobule to a greater extent. Conclusions: This study demonstrates clear functional differences of simple index finger tapping in early-stage TS. We suggest that this reflects the requirement for additional brain networks to keep a normal performance level during the actual task and adaptive mechanisms due to continuous tic suppression and performance in TS. (Contains 2 tables and 1 figure.)