A negative correlation between math anxiety and mathematics performance is frequently reported. Thus, some may assume that high levels of mathematics anxiety are associated with poor mathematical understanding. However, no previous research has clearly measured the association between mathematics anxiety and mathematical learning disability. To fill this gap, here we investigated the comorbidity of developmental dyscalculia (a selective, serious deficit in mathematical performance) and mathematics anxiety in a sample of 1,757 primary school (8- to 9-year-old) and secondary school (12- to 13-year-old) children. We found that children with developmental dyscalculia were twice as likely to have high mathematics anxiety as were children with typical mathematics performance. More girls had comorbid mathematics anxiety and developmental dyscalculia than did boys. However, 77% of children with high mathematics anxiety had typical or high mathematics performance. Our findings suggest that cognitive and emotional mathematics problems largely dissociate and call into question the assumption that high mathematics anxiety is exclusively linked to poor mathematics performance. Different intervention methods need to be developed to prevent and treat emotional and cognitive blocks of mathematical development.