It is common for people with bipolar disorder to experience delays of several years to diagnosis and appropriate treatment. Retrospective studies often report more than 10 years between the onset of illness and correct diagnosis being made. Similarly delays of many years before initiation of appropriate medication are described. Growing evidence indicates delayed diagnosis and treatment of bipolar disorder are associated withpoorer long-term outcomes. Understanding these delays better is key to devising appropriate strategies to remediate them. We recently studied the experience of a cohort of over 1300 UK patients from the South London and Maudsley NHS Foundation Trust (SLaM) Biomedical Research Centre Case Register. SLaM is Europe’s largest provider of secondary mental healthcare providing almost all secondary mental healthcare to a geographic catchment of approximately 1.2 million residents. Anonymized electronic clinical records were sought from new referrals to SLaM adult services who went on to receive a diagnosis of bipolar disorder. Over 1300 individuals with first presentation of bipolar disorder were included in this study. Delays between referral and diagnosis were relatively short and time to initiation of appropriate medication substantially better than that reported in recent studies elsewhere. This may in part be explained as the result of high severity of symptoms on presentation in many cases. These UK data suggest that substantially reducing the delay to diagnosis of bipolar disorder may require changes in healthcare provision before referral to secondary care and increased recognition of the importance of early hypomanic and manic symptoms.