Background: Genetic counselling and testing for Lynch syndrome have recently been introduced in several South American countries, though yet not available in the public health care system.Methods: We compiled data from publications and hereditary cancer registries to characterize the Lynch syndrome mutation spectrum in South America. In total, data from 267 families that fulfilled the Amsterdam criteria and/or the Bethesda guidelines from Argentina, Brazil, Chile, Colombia and Uruguay were included.Results: Disease-predisposing mutations were identified in 37% of the families and affected MLH1 in 60% and MSH2 in 40%. Half of the mutations have not previously been reported and potential founder effects were identified in Brazil and in Colombia.Conclusion: The South American Lynch syndrome mutation spectrum includes multiple new mutations, identifies potential founder effects and is useful for future development of genetic testing in this continent. © 2013 Dominguez-Valentin et al.; licensee BioMed Central Ltd.