Objective: To raise awareness of attention-deficit/hyperactivity disorder (ADHD) as an underdiagnosed, undertreated, often comorbid, and debilitating condition in adults.Data Sources: PubMed was searched using combinations of keywords, including ADHD, adult, diagnosis, identify, prevalence, and comorbid, to find articles published between 1976 and 2013.Study Selection: In total, 99 articles were selected for inclusion on the basis of their relevance to the objective and importance to and representation of ADHD research, including international guidelines for adults with ADHD.Results: In a large proportion of children with ADHD, symptoms persist into adulthood. However, although adults with ADHD often experience chaotic lifestyles, with impaired educational and vocational achievement and higher risks of substance abuse and imprisonment, many remain undiagnosed and/or untreated. ADHD is usually accompanied by other psychiatric comorbidities (such as major depressive disorder, anxiety disorder, and alcohol abuse). Indeed, adults with ADHD are more likely to present to a psychiatric clinic for treatment of their comorbid disorders than for ADHD, and their ADHD symptoms are often mistaken for those of their comorbidities. Untreated ADHD in adults with psychiatric comorbidities leads to poor clinical and functional outcomes for the patient even if comorbidities are treated. Effective treatment of adults’ ADHD improves symptoms, emotional lability, and patient functioning, often leading to favorable outcomes (eg, safer driving, reduced criminality). A few medications have now been approved for use in adults with ADHD, while a multimodal approach involving psychotherapy has also shown promising results.Conclusions General psychiatrists should familiarize themselves with the symptoms of ADHD in adults in order to diagnose and manage ADHD and comorbidities appropriately in these patients.