Attention deficit/hyperactivity disorder (ADHD) often persists into adulthood. Although its persistence and relative high prevalence, ADHD in adults is often underdiagnosed and undertreated in Italy, leading to poor clinical and functional outcomes, and higher costs of illness. The aims of the study were to identify the Italian mental health services for ADHD in adults, describe the diagnostic and treatment procedures they follow, and compare this offer with the recommendations of the German and English guidelines. The centres, that adopt a clinical and assessment protocol for adult ADHD diagnosis (carried out by specifically trained personnel) and prescribe pharmacological treatment for adult ADHD, were selected from the list of accredited services provided by the Appendix B.2 of the ISTISAN 16/37 Reports of the ISS. An ad-hoc survey including open-ended and close-ended questions was sent to each selected centre in February 2020. The overall picture resulting from the data analysis was compared with the recommendations of the German and English guidelines. The present survey shows that only a few centres are specialised in the diagnosis and treatment of ADHD in adults in Italy. Furthermore, there are no national guidelines for adult ADHD in Italy. The collected data also suggest that there is no a unified practice shared by the Centres both for the patient's transition from child and adolescent to adult mental health services and for the diagnostic-therapeutic process. It is therefore crucial to create specific protocols and develop national guidelines to better identify and diagnose ADHD in adults and provide targeted and more efficient multimodal treatments.