Objective: To examine the rates of psychiatric comorbidities within a New Zealand sample of adults with ADHD compared with a community control group. Method: We merged six data sets to obtain a sample of 222 adults (158 ADHD, 64 controls). Comorbidities were assessed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (4th ed. text rev. [DSM-IV-TR]) Axis-I disorders. Results: Both groups were equivalent in IQ, socioeconomic status, gender, education, income levels, and age. Lifetime rates of psychiatric disorders were significantly higher in the ADHD group (83%) versus the control group (52%) with higher rates of major depressive disorder (MDD; 65% vs. 36%), social phobia (31% vs. 11%), substance abuse (26% vs. 8%), and alcohol abuse (32% vs. 14%). Within the ADHD group, other than a group difference in specific phobias, there were no gender differences. Conclusion: The findings are consistent with international research; adults with ADHD in New Zealand have higher rates of psychiatric disorders than the general population.