The lack of specificity of attention-deficit/hyperactivity disorder (ADHD) symptoms represents a diagnostic challenge, especially when assessing psychiatric patients reporting a wide range of complaints. Rate of endorsement of ADHD symptoms, and their association with neuropsychological performance, was examined in a psychiatric sample of 71 adults, who had been referred for a neuropsychological evaluation. Patients completed two self-report measures of ADHD symptoms, the ADHD Self-Report Scale (ADHD-SR) and the Wender Utah Rating Scale-Short Form, as well as measures of attention, executive functioning, visuoconstructional ability, and verbal learning and memory. On the ADHD-SR, 74.6% of the sample met the cutoff for inattention or hyperactivity, while 81.7% met the cutoff for impulsivity. Neuropsychological performance was weakly associated with self-reported symptoms. Our results suggest that psychiatric patients commonly report symptoms of inattention, hyperactivity, and impulsivity. Assessment utilizing multiple sources is necessary to confirm whether self-reported symptoms are indicative of ADHD or reflect other causes.