Background Synchronous colorectal carcinoma has seldom been studied in large series. The study was designed to examine the significance of colorectal synchronous carcinoma in a large cohort of patients. Methods The clinicopathological features of 102 patients with synchronous colorectal carcinoma were compared with 1,793 patients with solitary colorectal carcinoma. Results The prevalence of synchronous colorectal carcinoma was 3.6%. In these patients, 4% had FAP, 6% had hyperplastic polyposis, and 2% had ulcerative colitis. The index carcinoma was more likely to have higher histological grade and T stage than other carcinoma(s) in the same patient. When compared with solitary colorectal carcinoma, synchronous colorectal carcinoma was more often noted in males with coexisting FAP and in proximal location. The 5-year survival rate of patients with synchronous colorectal carcinoma was 53% and was similar to those with solitary colorectal carcinoma. Conclusions We examined the clinicopathological features of patients with synchronous colorectal carcinomas in a large cohort of patients. Attention to these features was important for better management of this group of cancer.