Background: We recently adapted the published National institute for Health and Care Excellence (NICE) Attention deficit hyperactivity disorder (ADHD) diagnosis and management guideline to the Saudi Arabian context. It has been postulated that adaptation of evidence-based clinical practice guidelines to the local healthcare context rather than de-novo development will improve their adoption and implementation without imposing a significant burden on resources. The objective of this paper is to describe the adaptation process methodology utilized for the generation of the first national guideline for management of people with ADHD in Saudi Arabia.Methods: We used the KSU-Modified-ADAPTE methodology for the guideline adaptation process. We describe the full process in detail including the three phases of set-up, adaptation, and finalization. The process was conducted by a multidisciplinary guideline adaptation group in addition to an external review for the clinical content and methodology.Results: The group adapted ten main categories of recommendations from one source CPG (NICE). The recommendations include; (i) service organisation and training, (ii) recognition, identification and referral, (iii) diagnosis, (iv) support, (v) managing ADHD, (vi) dietary advice, (vii) medication, (viii) maintenance and monitoring, (ix) adherence to treatment, and (x) review of medication and discontinuation. Several implementation tools were compiled and developed to enhance implementability including a clinical algorithm, quality measures, coding system, medication tables, translations, patient information, and online resources.Conclusions: The finalized clinical practice guideline provides healthcare providers with applicable evidence-based guidance for the management of people with ADHD in Saudi Arabia. The project also demonstrated the effectiveness of KSU-Modified-ADAPTE, and emphasized the value of a collaborative clinical and methodological expert group for adaptation of national guidelines.