Objective: To estimate the prevalence of PDs according to Millon’s evolution-based model among adult ADHD outpatients. Method: Cross-sectional study of consecutive patients referred to an adult ADHD clinic. PDs were evaluated with Millon Clinical Multiaxial Inventory–III (MCMI-III). Results: One-hundred-eighty-one participants had valid MCMI-III, of whom147 were diagnosed with ADHD. Mean age: 32.97, SD:11.56, females: 74 (50.3%). Among the 147 participants with ADHD, 29 (19.7%) did not meet criteria for any PD, 43 (29.3%) met the criteria for one PD, 34 (23.1%) for two PDs and the rest three or more. Most common PD was Dependent ( n = 58) followed by Depressive ( n = 45). Inattentive sub-type was associated with dependent PD, while combined type with antisocial, negativistic (passive/aggressive) and sadistic PD. Conclusion: Particular personality profiles were more common with different ADHD subtypes. Given the developmental origins of PD, further research may help identify possible links with childhood difficulties.