Remission should be the goal of attention-deficit hyperactivity disorder (ADHD) treatment. However, there is no universally accepted definition of remission in ADHD, although clinical studies use a number of criteria. This article examines current research into the concept of remission in ADHD by reviewing the literature for definition and achievement of remission in children and adults with ADHD. Results demonstrate that the concept of remission in ADHD has been proposed by several study groups, using thresholds of validated rating scales to indicate syndromic, symptomatic and functional remission. Several studies have demonstrated the achievement of remission in ADHD children utilizing methylphenidate delivered by an osmotic, controlled-release formulation (OROS®) and atomoxetine. However, none has defined a time period over which these criteria must be met for an individual with ADHD to be considered 'in remission'. Standardized remission criteria in ADHD will provide a tool for assessing the effectiveness of treatments for ADHD, and raise treatment standards.