The NICE Guideline on ADHD published in 2008 represents a major advance in evidence-based healthcare for children, young people and adults with ADHD. It draws together systematic reviews and expert opinion to produce clinical practice recommendations covering diagnosis, behavioural and pharmacological treatment and organisation of services for children and adults. This article summarises the key practice recommendations, highlights where gaps remain in the evidence base and describes some of the challenges for implementing the guideline in routine clinical practice. Some of the key recommendations of the NICE guideline are that ADHD should only be diagnosed by specialists in secondary care, that parent training/education should be used as first-line management in those with moderate ADHD but medication may be offered as first-line line treatment for severe ADHD, alongside other management strategies. The recommended medications are methylphenidate, atomoxetine and dexamfetamine. Attention is drawn to the fact that ADHD can occur in the presence of co-existing conditions such as learning disability and autism spectrum disorder.