Long waiting times from early symptoms to diagnosis and treatment may influence the staging and prognosis of patients with colorectal cancer. We analyzed the effect of colonoscopy timing on the outcome of these patients. This study aimed to compare the outcome (tumoral staging and long-term survival) of patients with suspected colorectal cancer according to diagnostic colonoscopy timing. This study is an analysis of a prospectively maintained database. The study was conducted at the Open Access Endoscopy Service of the tertiary public healthcare center Hospital Universitario de Canarias, in the Spanish island of Tenerife. Consecutive patients diagnosed of colorectal cancer between February 2008 and October 2010, fulfilling 1 or more National Institute for Health and Clinical Excellence criteria, were assigned to early colonoscopy (<30 days from referral) or to standard-schedule colonoscopy at the discretion of the referring physician. Tumor staging (TNM classification) at diagnosis and long-term survival after treatment were compared in both strategies. The primary outcomes measured were the stage at presentation and overall survival, as determined by prompt or standard referral. Overall, 257 patients with colorectal cancer were diagnosed (101 at early colonoscopy and 156 at standard-schedule colonoscopy). TNM stages I and II were found in 52 (54.2%) and 60 (41.7%) patients in the early colonoscopy group and standard-schedule colonoscopy group. Stage IV was confirmed in 13 patients (13.5%) diagnosed in the early colonoscopy group and in 40 (28%) detected in the standard-schedule colonoscopy group. Survival rates at 12 and 60 months after treatment were significantly higher in the early colonoscopy group compared with the standard-schedule colonoscopy group (p < 0.001). Controlled randomization of early versus standard-referral colonoscopy, size and scope of analysis, the time interval from symptom onset to first physician assessment, and the different locations of colorectal cancer between groups were limitations of the study. Colonoscopy within 30 days from referral improves outcome in patients with symptomatic colorectal cancer. See Video Abstract at http://journals.lww.com/dcrjournal/Pages/videogallery.aspx.