Several million children and a growing number of adults are currently being treated for attention-deficit hyperactivity disorder (ADHD) worldwide. Concerns have been expressed about possible cardiac effects of the common treatments, namely methylphenidate, amphetamines and atomoxetine. Small increases in mean heart rate (HR) and mean blood pressure (BP) have been reported for all three drugs, but most of the studies have not yielded statistically significant results. These studies also have limitations, particularly regarding the lack of accepted and standardised measurement methods. Several large studies of the very rare phenomenon of sudden death in children have failed to show any convincing association with ADHD treatment. Whether minor increases in HR and BP have a cumulative effect over many years and have a long-term adverse effect on cardiovascular health remains undetermined.