This paper examines diagnostic timelines for people suspected of having ALS/MND over a 20-year period, evaluates the impact of a ‘fast track’ diagnostic process and discusses typical causes of diagnostic delay. Key diagnostic timelines (dates of first symptom, diagnosis and death) were reviewed for people diagnosed between 1989 and 2008. Patients evaluated through a fast-track diagnostic process and those investigated through traditional neurology clinics were compared. Typical causes of diagnostic delay were investigated. Results showed that diagnostic timelines have been surprisingly consistent over this 20-year period. Time from first symptom to diagnosis hovered around 12 months, with the diagnosis typically being made around the midpoint (50% of total disease duration elapsed) of the disease pathway. The introduction of a fast-track process has not to date affected overall performance but has shortened times from referral to diagnosis. Diagnostic delays appear to be associated with clinical complexity and delays in referral, both within primary and secondary care services. In conclusion, more widespread implementation of fast-track processes could potentially reduce diagnostic delays. Educational interventions among health care professionals both in primary and secondary care may also help shorten diagnostic pathways.