Objective: To explore the differences in baseline respiratory sinus arrhythmia (RSA) between children with fetal alcohol spectrum disorder (FASD) and typically developing children (TDC) and to investigate whether children with FASD have the capacity to engage in a brief mindfulness exercise. Methods: Participants were 14 children with FASD and 20 TDC. RSA was measured at baseline, during, and following a mindfulness exercise. A mindfulness compliance checklist was completed to ascertain if children could follow the task instructions. Results: Both groups obtained high scores on the mindfulness compliance checklist. There was a trend for children with FASD to have lower baseline RSA compared to TDC. Children in both groups demonstrated an increase in RSA during the mindfulness task. Conclusions: Children with FASD could engage in a mindfulness task, and both groups showed an increase in RSA. Further research is needed to establish whether prolonged mindfulness practice could be beneficial.