Colorectal cancer (CRC) is extremely infrequent in children and adolescents. There is little information about this entity, mainly case reports and review articles. We describe three cases of children with poor-differentiated colorectal carcinoma and advanced disease at onset. The presenting symptoms were abdominal pain and constipation, with a median of latency of symptoms of 4-48 months. None of these patients had operable disease at onset; having a disease progression despite therapy in two cases. This study reaffirms poor prognosis of pediatric CRC, probably due to an aggressive tumoral biology and advanced stage at diagnosis. Therapeutic guidelines are based in adult treatment; therefore, efforts should be made to improve tools in early diagnosis and future therapies for a better survival in childhood.