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OBJECTIVE Conditional survival accounts for the time already survived after surgery and provides additional survival information. The aim was to assess conditional survival in stages I-III early onset colorectal cancer patients and to create nomograms predicting the conditional overall survival and cancer-specific survival after surgery. METHODS A total of 7058 patients who underwent surgical resection of early onset colorectal cancer were identified from surveillance, epidemiology and end results database. The formula used for conditional survival calculation was conditional survival(x|y) = S(x + y)/S(x), where S(x) represents the survival at x years. Conditional survival nomograms were then developed to predict the 5-year conditional overall survival and cancer-specific survival. RESULTS The 5-year overall survival and cancer-specific survival after surgery increases gradually with additional survival time. Race, tumour site, grade, histology, T stage, N stage, lymph node ratio, preoperative carcinoma embryonic antigen level and perineural invasion status were independent predictors of cancer-specific survival, while age and sex were another two independent risk factors for overall survival. The nomograms based on these factors were successfully developed to predict 5-year overall survival and cancer-specific survival given 1-4 years already survived. CONCLUSION The probability of achieving postoperative 5-year overall survival and cancer-specific survival for early onset colorectal cancer increases gradually with additional time survived. The developed nomograms are fairly valuable and informative in facilitating clinical treatment and follow-up schemes.