Genetic screening of cancer genes in Latin America has been performed during the last 10-15 years and has mainly focused on breast and colorectal cancer. All studies have varied in relation to sample sizes, patient selection criteria, and experimental approaches. Besides all of these variables, relevant information has been gathered for both types of hereditary cancer permitting advances in clinical decisions based on genetic diagnosis in countries were these studies have been performed. For hereditary breast cancer cases patient carriers for BRCA1 or BRCA2 mutations vary between 13.7% and 26.3%. In the case of Lynch syndrome, using Amsterdam criteria, the percentage of mutation carriers for MLH1, MSH2, PMS2, MSH6 and EPCAM is 57.4%. For familial adenomatous polyposis patients, the respective percentages for mutation carriers are 79% and 40% for classical and attenuated phenotype.