To investigate the value of routine colonoscopy, post-computed tomography (CT) confirmed diverticulitis. The current practice is to scope patients 6-8 weeks post an episode of acute diverticulitis. We hypothesise that this practice has a relatively low value.A retrospective cohort study was conducted on adult patients presenting acute diverticulitis n = 1680 (uncomplicated = 1005, complicated = 675) between January 2017 and July 2019 at three tertiary hospitals in Perth. The National Bowel Cancer Screening Program (NBCSP) positive cases were the reference group (n = 1800). Data were analysed using SPSS v.27.One thousand two hundred seventy-two patients had a subsequent colonoscopy during the follow-up period, of which 24% (n = 306) were uncomplicated diverticulitis, 34% (n = 432) complicated diverticulitis, and 42% (n = 534) as the reference cohort. Patient demographics were similar between centres and subgroups. Incidence of primary colorectal cancer (CRC) was n = 3 (1.0%), n = 9 (2.1%), and n = 10 (1.9%) for uncomplicated diverticulitis, complicated diverticulitis, and NBCSP, respectively (p = 0.50). Subgroup analysis by age revealed a statistically significant higher rate of negative colonoscopy in uncomplicated diverticulitis patients aged over 50.Routine colonoscopy for patients with uncomplicated diverticulitis is not a cost-effective strategy for colorectal cancer screening patients over 50 years. These patients should participate in the NBCSP with biennial FOBT instead. We suggest continuing routine endoscopic evaluation for patients with uncomplicated diverticulitis under 50 years and all patients admitted with complicated diverticulitis.