Medications are considered the primary treatment for symptoms of adult attention-deficit/ hyperactivity disorder (ADHD), although medications alone may not produce sufficient functional improvements for many patients. Moreover, some adults with ADHD decline pharmacotherapy due to lack of response, side effects, medical contraindication, or personal choice. This article reports on the clinical outcomes of five adults with ADHD who completed cognitive behavioral therapy (CBT) without concurrent medication treatment. Nonparametric analysis of pretreatment and posttreatment clinical data indicated significant improvements on various measures of ADHD symptoms, overall functioning, depression, and anxiety. Although limited by the small sample size, the current pilot study provides preliminary evidence that CBT may be helpful for adults with ADHD who decline or are unable to take medications in cases in which their symptoms and impairments are relatively mild and uncomplicated. The limitations of this open pilot study and directions for future research also are discussed.