Purpose <p>This study described the presenting features, initial assessment, hospital care, and complications at discharge among Australian adolescents and young adults with Invasive meningococcal disease (IMD).</p> Methods <p>We conducted a retrospective study of IMD cases aged 15–25 years admitted between 2005 and 2018 in ten Australian hospitals.</p> Results <p>A total of 104 IMD cases were included; 95.2% were due to serogroup B, and the mean age was 19.3 years (SD 2.1). Initial assessment most commonly occurred in the emergency department following self-presentation/private transport (50.0%), followed by general practice (32.4%) and paramedic-led pre-hospital care (17.7%). The most common nonspecific presenting symptoms were headache (80.8%), vomiting or nausea (75.0%), and fever (72.1%), and category 3 was the most frequently assigned triage level (40.6%). Half of cases required ICU admission (50.0%), with a mean ICU stay of 2.8 days (SD 2.4). Compared with patients who self-presented to the emergency department, initial assessment by paramedics in the community was associated with higher odds of ICU admission (adjusted AOR 4.42, 95% CI 1.81 to 16.5). A delay of more than 1&#xa0;day between symptom onset and first medical presentation was associated with higher odds of discharge with one or more complications (aOR 2.88, 95% CI 1.13 to 7.35). At discharge, 43.3% had at least one complication, most commonly neurological sequelae (55.6% of those with complications), and 2 cases (1.9%) died.</p> Conclusion <p>Delayed presentation was associated with a higher risk of IMD complications, highlighting the importance of early assessment and timely management to improve outcomes.</p> Clinical trial registration <p>Clinicaltrails.gov, NCT03798574, <a href="https://clinicaltrials.gov/study/NCT03798574">https://clinicaltrials.gov/study/NCT03798574</a>.</p>