Exposure to heavy metals has been associated with affecting children's neurodevelopment, particularly increasing the risk of developing attention-deficit hyperactivity disorder (ADHD). The current exploratory study aims to investigate potential associations between presence of 15 different heavy metals in urine and ADHD. A total of 190 urine samples of participants from clinical and non-clinical population (non-ADHD = 66; ADHD = 124) aged between 6 and 15 years from Barcelona and Tarragona (Spain) were analysed. Logistic regressions adjusted by sex, age, SES, BMI and diet quality were performed. Highest quartiles (3rd and 4th) of Pb (lead) (aOR 5.33; CI [1.89, 14.98]), Cd (cadmium) (aOR 3.69, CI [1.38, 9.83]), Cu (copper) (aOR 16.46, CI [4.66, 58.14]) and Sb (antimony) (aOR 3.04, CI [1.12, 8.23]) were significantly associated with increased odds of ADHD DSM-5 diagnosis. Additionally, Cu and Cd were associated with higher scores of inattention symptoms. Whereas, Cu and Sb were associated with hyperactivity-impulsivity severity. This exploratory study provides preliminary valuable evidence, suggesting potential associations between environmental factors, such as metal exposure, with ADHD in school-aged children. These findings highlight the importance of further research to support these associations and, if confirmed, explore strategies to mitigate the potential impacts of these toxicants on children's health.