Introduction. Population-based cancer registries provide vital information for planning, prevention and cancer management. Information generated by the registries must be comprehensive, valid and comparable. Because of their importance, regular quality assessments are recommended. Objective. The quality of cancer incidence data were assessed at four population-based cancer registries in Colombia for cancer incidence estimations. Material and methods. Data collected at population-based cancer registries of Bucaramanga, Cali, Pasto, and Manizales were included. Completeness was assessed by the use of graphs in illustrating the mortality incidence ratios and their relation to the survival. Validity was evaluated by the description of morphologically verified cases, cases identified from death certificates only, and the internal consistency of the data. Results. There was a global under-coverage of cancer registration at Bucaramanga and Manizales, whereas a more specific under-coverage for certain localizations was observed in Cali and Pasto. Validity analyses established that death certificates were little used as a source of information, and some inconsistencies appeared among the data associated with the most valid basis of diagnosis and morphology. Conclusions. In Colombia, the data quality at population-based cancer registries can be further improved by considering the use of additional sources of information, such as death certificates, the use of specialized software for data capture, and automatic validation of internal consistency. Mortality certification must be improved in areas where a population-based cancer registry is operating.